Actual source code: snes.c
  1: #include <petsc/private/snesimpl.h>
  2: #include <petscdmshell.h>
  3: #include <petscdraw.h>
  4: #include <petscds.h>
  5: #include <petscdmadaptor.h>
  6: #include <petscconvest.h>
  8: PetscBool         SNESRegisterAllCalled = PETSC_FALSE;
  9: PetscFunctionList SNESList              = NULL;
 11: /* Logging support */
 12: PetscClassId  SNES_CLASSID, DMSNES_CLASSID;
 13: PetscLogEvent SNES_Solve, SNES_SetUp, SNES_FunctionEval, SNES_JacobianEval, SNES_NGSEval, SNES_NGSFuncEval, SNES_NewtonALEval, SNES_NPCSolve, SNES_ObjectiveEval;
 15: /*@
 16:   SNESSetErrorIfNotConverged - Causes `SNESSolve()` to generate an error immediately if the solver has not converged.
 18:   Logically Collective
 20:   Input Parameters:
 21: + snes - iterative context obtained from `SNESCreate()`
 22: - flg  - `PETSC_TRUE` indicates you want the error generated
 24:   Options Database Key:
 25: . -snes_error_if_not_converged <true,false> - cause an immediate error condition and stop the program if the solver does not converge
 27:   Level: intermediate
 29:   Note:
 30:   Normally PETSc continues if a solver fails to converge, you can call `SNESGetConvergedReason()` after a `SNESSolve()`
 31:   to determine if it has converged. Otherwise the solution may be inaccurate or wrong
 33: .seealso: [](ch_snes), `SNES`, `SNESGetErrorIfNotConverged()`, `KSPGetErrorIfNotConverged()`, `KSPSetErrorIfNotConverged()`
 34: @*/
 35: PetscErrorCode SNESSetErrorIfNotConverged(SNES snes, PetscBool flg)
 36: {
 37:   PetscFunctionBegin;
 40:   snes->errorifnotconverged = flg;
 41:   PetscFunctionReturn(PETSC_SUCCESS);
 42: }
 44: /*@
 45:   SNESGetErrorIfNotConverged - Indicates if `SNESSolve()` will generate an error if the solver does not converge?
 47:   Not Collective
 49:   Input Parameter:
 50: . snes - iterative context obtained from `SNESCreate()`
 52:   Output Parameter:
 53: . flag - `PETSC_TRUE` if it will generate an error, else `PETSC_FALSE`
 55:   Level: intermediate
 57: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESSetErrorIfNotConverged()`, `KSPGetErrorIfNotConverged()`, `KSPSetErrorIfNotConverged()`
 58: @*/
 59: PetscErrorCode SNESGetErrorIfNotConverged(SNES snes, PetscBool *flag)
 60: {
 61:   PetscFunctionBegin;
 63:   PetscAssertPointer(flag, 2);
 64:   *flag = snes->errorifnotconverged;
 65:   PetscFunctionReturn(PETSC_SUCCESS);
 66: }
 68: /*@
 69:   SNESSetAlwaysComputesFinalResidual - tells the `SNES` to always compute the residual (nonlinear function value) at the final solution
 71:   Logically Collective
 73:   Input Parameters:
 74: + snes - the shell `SNES`
 75: - flg  - `PETSC_TRUE` to always compute the residual
 77:   Level: advanced
 79:   Note:
 80:   Some solvers (such as smoothers in a `SNESFAS`) do not need the residual computed at the final solution so skip computing it
 81:   to save time.
 83: .seealso: [](ch_snes), `SNES`, `SNESFAS`, `SNESSolve()`, `SNESGetAlwaysComputesFinalResidual()`
 84: @*/
 85: PetscErrorCode SNESSetAlwaysComputesFinalResidual(SNES snes, PetscBool flg)
 86: {
 87:   PetscFunctionBegin;
 89:   snes->alwayscomputesfinalresidual = flg;
 90:   PetscFunctionReturn(PETSC_SUCCESS);
 91: }
 93: /*@
 94:   SNESGetAlwaysComputesFinalResidual - checks if the `SNES` always computes the residual at the final solution
 96:   Logically Collective
 98:   Input Parameter:
 99: . snes - the `SNES` context
101:   Output Parameter:
102: . flg - `PETSC_TRUE` if the residual is computed
104:   Level: advanced
106: .seealso: [](ch_snes), `SNES`, `SNESFAS`, `SNESSolve()`, `SNESSetAlwaysComputesFinalResidual()`
107: @*/
108: PetscErrorCode SNESGetAlwaysComputesFinalResidual(SNES snes, PetscBool *flg)
109: {
110:   PetscFunctionBegin;
112:   *flg = snes->alwayscomputesfinalresidual;
113:   PetscFunctionReturn(PETSC_SUCCESS);
114: }
116: /*@
117:   SNESSetFunctionDomainError - tells `SNES` that the input vector, a proposed new solution, to your function you provided to `SNESSetFunction()` is not
118:   in the functions domain. For example, a step with negative pressure.
120:   Logically Collective
122:   Input Parameter:
123: . snes - the `SNES` context
125:   Level: advanced
127:   Notes:
128:   If this is called the `SNESSolve()` stops iterating and returns with a `SNESConvergedReason` of `SNES_DIVERGED_FUNCTION_DOMAIN`
130:   You should always call `SNESGetConvergedReason()` after each `SNESSolve()` and verify if the iteration converged (positive result) or diverged (negative result).
132:   You can direct `SNES` to avoid certain steps by using `SNESVISetVariableBounds()`, `SNESVISetComputeVariableBounds()` or
133:   `SNESLineSearchSetPreCheck()`, `SNESLineSearchSetPostCheck()`
135: .seealso: [](ch_snes), `SNESCreate()`, `SNESSetFunction()`, `SNESFunctionFn`, `SNESSetJacobianDomainError()`, `SNESVISetVariableBounds()`,
136:           `SNESVISetComputeVariableBounds()`, `SNESLineSearchSetPreCheck()`, `SNESLineSearchSetPostCheck()`, `SNESConvergedReason`, `SNESGetConvergedReason()`
137: @*/
138: PetscErrorCode SNESSetFunctionDomainError(SNES snes)
139: {
140:   PetscFunctionBegin;
142:   PetscCheck(!snes->errorifnotconverged, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "User code indicates input vector is not in the function domain");
143:   snes->domainerror = PETSC_TRUE;
144:   PetscFunctionReturn(PETSC_SUCCESS);
145: }
147: /*@
148:   SNESSetJacobianDomainError - tells `SNES` that the function you provided to `SNESSetJacobian()` at the proposed step. For example there is a negative element transformation.
150:   Logically Collective
152:   Input Parameter:
153: . snes - the `SNES` context
155:   Level: advanced
157:   Notes:
158:   If this is called the `SNESSolve()` stops iterating and returns with a `SNESConvergedReason` of `SNES_DIVERGED_FUNCTION_DOMAIN`
160:   You should always call `SNESGetConvergedReason()` after each `SNESSolve()` and verify if the iteration converged (positive result) or diverged (negative result).
162:   You can direct `SNES` to avoid certain steps by using `SNESVISetVariableBounds()`, `SNESVISetComputeVariableBounds()` or
163:   `SNESLineSearchSetPreCheck()`, `SNESLineSearchSetPostCheck()`
165: .seealso: [](ch_snes), `SNESCreate()`, `SNESSetFunction()`, `SNESFunctionFn`, `SNESSetFunctionDomainError()`, `SNESVISetVariableBounds()`,
166:           `SNESVISetComputeVariableBounds()`, `SNESLineSearchSetPreCheck()`, `SNESLineSearchSetPostCheck()`, `SNESConvergedReason`, `SNESGetConvergedReason()`
167: @*/
168: PetscErrorCode SNESSetJacobianDomainError(SNES snes)
169: {
170:   PetscFunctionBegin;
172:   PetscCheck(!snes->errorifnotconverged, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "User code indicates computeJacobian does not make sense");
173:   snes->jacobiandomainerror = PETSC_TRUE;
174:   PetscFunctionReturn(PETSC_SUCCESS);
175: }
177: /*@
178:   SNESSetCheckJacobianDomainError - tells `SNESSolve()` whether to check if the user called `SNESSetJacobianDomainError()` Jacobian domain error after
179:   each Jacobian evaluation. By default, it checks for the Jacobian domain error in the debug mode, and does not check it in the optimized mode.
181:   Logically Collective
183:   Input Parameters:
184: + snes - the `SNES` context
185: - flg  - indicates if or not to check Jacobian domain error after each Jacobian evaluation
187:   Level: advanced
189:   Note:
190:   Checks require one extra parallel synchronization for each Jacobian evaluation
192: .seealso: [](ch_snes), `SNES`, `SNESConvergedReason`, `SNESCreate()`, `SNESSetFunction()`, `SNESFunctionFn`, `SNESSetFunctionDomainError()`, `SNESGetCheckJacobianDomainError()`
193: @*/
194: PetscErrorCode SNESSetCheckJacobianDomainError(SNES snes, PetscBool flg)
195: {
196:   PetscFunctionBegin;
198:   snes->checkjacdomainerror = flg;
199:   PetscFunctionReturn(PETSC_SUCCESS);
200: }
202: /*@
203:   SNESGetCheckJacobianDomainError - Get an indicator whether or not `SNES` is checking Jacobian domain errors after each Jacobian evaluation.
205:   Logically Collective
207:   Input Parameter:
208: . snes - the `SNES` context
210:   Output Parameter:
211: . flg - `PETSC_FALSE` indicates that it is not checking Jacobian domain errors after each Jacobian evaluation
213:   Level: advanced
215: .seealso: [](ch_snes), `SNES`, `SNESCreate()`, `SNESSetFunction()`, `SNESFunctionFn`, `SNESSetFunctionDomainError()`, `SNESSetCheckJacobianDomainError()`
216: @*/
217: PetscErrorCode SNESGetCheckJacobianDomainError(SNES snes, PetscBool *flg)
218: {
219:   PetscFunctionBegin;
221:   PetscAssertPointer(flg, 2);
222:   *flg = snes->checkjacdomainerror;
223:   PetscFunctionReturn(PETSC_SUCCESS);
224: }
226: /*@
227:   SNESGetFunctionDomainError - Gets the status of the domain error after a call to `SNESComputeFunction()`
229:   Logically Collective
231:   Input Parameter:
232: . snes - the `SNES` context
234:   Output Parameter:
235: . domainerror - Set to `PETSC_TRUE` if there's a domain error; `PETSC_FALSE` otherwise.
237:   Level: developer
239: .seealso: [](ch_snes), `SNES`, `SNESSetFunctionDomainError()`, `SNESComputeFunction()`
240: @*/
241: PetscErrorCode SNESGetFunctionDomainError(SNES snes, PetscBool *domainerror)
242: {
243:   PetscFunctionBegin;
245:   PetscAssertPointer(domainerror, 2);
246:   *domainerror = snes->domainerror;
247:   PetscFunctionReturn(PETSC_SUCCESS);
248: }
250: /*@
251:   SNESGetJacobianDomainError - Gets the status of the Jacobian domain error after a call to `SNESComputeJacobian()`
253:   Logically Collective
255:   Input Parameter:
256: . snes - the `SNES` context
258:   Output Parameter:
259: . domainerror - Set to `PETSC_TRUE` if there's a Jacobian domain error; `PETSC_FALSE` otherwise.
261:   Level: advanced
263: .seealso: [](ch_snes), `SNES`, `SNESSetFunctionDomainError()`, `SNESComputeFunction()`, `SNESGetFunctionDomainError()`
264: @*/
265: PetscErrorCode SNESGetJacobianDomainError(SNES snes, PetscBool *domainerror)
266: {
267:   PetscFunctionBegin;
269:   PetscAssertPointer(domainerror, 2);
270:   *domainerror = snes->jacobiandomainerror;
271:   PetscFunctionReturn(PETSC_SUCCESS);
272: }
274: /*@
275:   SNESLoad - Loads a `SNES` that has been stored in `PETSCVIEWERBINARY` with `SNESView()`.
277:   Collective
279:   Input Parameters:
280: + snes   - the newly loaded `SNES`, this needs to have been created with `SNESCreate()` or
281:            some related function before a call to `SNESLoad()`.
282: - viewer - binary file viewer, obtained from `PetscViewerBinaryOpen()`
284:   Level: intermediate
286:   Note:
287:   The `SNESType` is determined by the data in the file, any type set into the `SNES` before this call is ignored.
289: .seealso: [](ch_snes), `SNES`, `PetscViewer`, `SNESCreate()`, `SNESType`, `PetscViewerBinaryOpen()`, `SNESView()`, `MatLoad()`, `VecLoad()`
290: @*/
291: PetscErrorCode SNESLoad(SNES snes, PetscViewer viewer)
292: {
293:   PetscBool isbinary;
294:   PetscInt  classid;
295:   char      type[256];
296:   KSP       ksp;
297:   DM        dm;
298:   DMSNES    dmsnes;
300:   PetscFunctionBegin;
303:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERBINARY, &isbinary));
304:   PetscCheck(isbinary, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Invalid viewer; open viewer with PetscViewerBinaryOpen()");
306:   PetscCall(PetscViewerBinaryRead(viewer, &classid, 1, NULL, PETSC_INT));
307:   PetscCheck(classid == SNES_FILE_CLASSID, PetscObjectComm((PetscObject)snes), PETSC_ERR_ARG_WRONG, "Not SNES next in file");
308:   PetscCall(PetscViewerBinaryRead(viewer, type, 256, NULL, PETSC_CHAR));
309:   PetscCall(SNESSetType(snes, type));
310:   PetscTryTypeMethod(snes, load, viewer);
311:   PetscCall(SNESGetDM(snes, &dm));
312:   PetscCall(DMGetDMSNES(dm, &dmsnes));
313:   PetscCall(DMSNESLoad(dmsnes, viewer));
314:   PetscCall(SNESGetKSP(snes, &ksp));
315:   PetscCall(KSPLoad(ksp, viewer));
316:   PetscFunctionReturn(PETSC_SUCCESS);
317: }
319: #include <petscdraw.h>
320: #if defined(PETSC_HAVE_SAWS)
321: #include <petscviewersaws.h>
322: #endif
324: /*@
325:   SNESViewFromOptions - View a `SNES` based on values in the options database
327:   Collective
329:   Input Parameters:
330: + A    - the `SNES` context
331: . obj  - Optional object that provides the options prefix for the checks
332: - name - command line option
334:   Level: intermediate
336: .seealso: [](ch_snes), `SNES`, `SNESView`, `PetscObjectViewFromOptions()`, `SNESCreate()`
337: @*/
338: PetscErrorCode SNESViewFromOptions(SNES A, PetscObject obj, const char name[])
339: {
340:   PetscFunctionBegin;
342:   PetscCall(PetscObjectViewFromOptions((PetscObject)A, obj, name));
343:   PetscFunctionReturn(PETSC_SUCCESS);
344: }
346: PETSC_EXTERN PetscErrorCode SNESComputeJacobian_DMDA(SNES, Vec, Mat, Mat, void *);
348: /*@
349:   SNESView - Prints or visualizes the `SNES` data structure.
351:   Collective
353:   Input Parameters:
354: + snes   - the `SNES` context
355: - viewer - the `PetscViewer`
357:   Options Database Key:
358: . -snes_view - Calls `SNESView()` at end of `SNESSolve()`
360:   Level: beginner
362:   Notes:
363:   The available visualization contexts include
364: +     `PETSC_VIEWER_STDOUT_SELF` - standard output (default)
365: -     `PETSC_VIEWER_STDOUT_WORLD` - synchronized standard
366:   output where only the first processor opens
367:   the file.  All other processors send their
368:   data to the first processor to print.
370:   The available formats include
371: +     `PETSC_VIEWER_DEFAULT` - standard output (default)
372: -     `PETSC_VIEWER_ASCII_INFO_DETAIL` - more verbose output for `SNESNASM`
374:   The user can open an alternative visualization context with
375:   `PetscViewerASCIIOpen()` - output to a specified file.
377:   In the debugger you can do "call `SNESView`(snes,0)" to display the `SNES` solver. (The same holds for any PETSc object viewer).
379: .seealso: [](ch_snes), `SNES`, `SNESLoad()`, `SNESCreate()`, `PetscViewerASCIIOpen()`
380: @*/
381: PetscErrorCode SNESView(SNES snes, PetscViewer viewer)
382: {
383:   SNESKSPEW     *kctx;
384:   KSP            ksp;
385:   SNESLineSearch linesearch;
386:   PetscBool      iascii, isstring, isbinary, isdraw;
387:   DMSNES         dmsnes;
388: #if defined(PETSC_HAVE_SAWS)
389:   PetscBool issaws;
390: #endif
392:   PetscFunctionBegin;
394:   if (!viewer) PetscCall(PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes), &viewer));
396:   PetscCheckSameComm(snes, 1, viewer, 2);
398:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &iascii));
399:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERSTRING, &isstring));
400:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERBINARY, &isbinary));
401:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERDRAW, &isdraw));
402: #if defined(PETSC_HAVE_SAWS)
403:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERSAWS, &issaws));
404: #endif
405:   if (iascii) {
406:     SNESNormSchedule normschedule;
407:     DM               dm;
408:     SNESJacobianFn  *cJ;
409:     void            *ctx;
410:     const char      *pre = "";
412:     PetscCall(PetscObjectPrintClassNamePrefixType((PetscObject)snes, viewer));
413:     if (!snes->setupcalled) PetscCall(PetscViewerASCIIPrintf(viewer, "  SNES has not been set up so information may be incomplete\n"));
414:     if (snes->ops->view) {
415:       PetscCall(PetscViewerASCIIPushTab(viewer));
416:       PetscUseTypeMethod(snes, view, viewer);
417:       PetscCall(PetscViewerASCIIPopTab(viewer));
418:     }
419:     if (snes->max_funcs == PETSC_UNLIMITED) {
420:       PetscCall(PetscViewerASCIIPrintf(viewer, "  maximum iterations=%" PetscInt_FMT ", maximum function evaluations=unlimited\n", snes->max_its));
421:     } else {
422:       PetscCall(PetscViewerASCIIPrintf(viewer, "  maximum iterations=%" PetscInt_FMT ", maximum function evaluations=%" PetscInt_FMT "\n", snes->max_its, snes->max_funcs));
423:     }
424:     PetscCall(PetscViewerASCIIPrintf(viewer, "  tolerances: relative=%g, absolute=%g, solution=%g\n", (double)snes->rtol, (double)snes->abstol, (double)snes->stol));
425:     if (snes->usesksp) PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of linear solver iterations=%" PetscInt_FMT "\n", snes->linear_its));
426:     PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of function evaluations=%" PetscInt_FMT "\n", snes->nfuncs));
427:     PetscCall(SNESGetNormSchedule(snes, &normschedule));
428:     if (normschedule > 0) PetscCall(PetscViewerASCIIPrintf(viewer, "  norm schedule %s\n", SNESNormSchedules[normschedule]));
429:     if (snes->gridsequence) PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of grid sequence refinements=%" PetscInt_FMT "\n", snes->gridsequence));
430:     if (snes->ksp_ewconv) {
431:       kctx = (SNESKSPEW *)snes->kspconvctx;
432:       if (kctx) {
433:         PetscCall(PetscViewerASCIIPrintf(viewer, "  Eisenstat-Walker computation of KSP relative tolerance (version %" PetscInt_FMT ")\n", kctx->version));
434:         PetscCall(PetscViewerASCIIPrintf(viewer, "    rtol_0=%g, rtol_max=%g, threshold=%g\n", (double)kctx->rtol_0, (double)kctx->rtol_max, (double)kctx->threshold));
435:         PetscCall(PetscViewerASCIIPrintf(viewer, "    gamma=%g, alpha=%g, alpha2=%g\n", (double)kctx->gamma, (double)kctx->alpha, (double)kctx->alpha2));
436:       }
437:     }
438:     if (snes->lagpreconditioner == -1) {
439:       PetscCall(PetscViewerASCIIPrintf(viewer, "  Preconditioned is never rebuilt\n"));
440:     } else if (snes->lagpreconditioner > 1) {
441:       PetscCall(PetscViewerASCIIPrintf(viewer, "  Preconditioned is rebuilt every %" PetscInt_FMT " new Jacobians\n", snes->lagpreconditioner));
442:     }
443:     if (snes->lagjacobian == -1) {
444:       PetscCall(PetscViewerASCIIPrintf(viewer, "  Jacobian is never rebuilt\n"));
445:     } else if (snes->lagjacobian > 1) {
446:       PetscCall(PetscViewerASCIIPrintf(viewer, "  Jacobian is rebuilt every %" PetscInt_FMT " SNES iterations\n", snes->lagjacobian));
447:     }
448:     PetscCall(SNESGetDM(snes, &dm));
449:     PetscCall(DMSNESGetJacobian(dm, &cJ, &ctx));
450:     if (snes->mf_operator) {
451:       PetscCall(PetscViewerASCIIPrintf(viewer, "  Jacobian is applied matrix-free with differencing\n"));
452:       pre = "Preconditioning ";
453:     }
454:     if (cJ == SNESComputeJacobianDefault) {
455:       PetscCall(PetscViewerASCIIPrintf(viewer, "  %sJacobian is built using finite differences one column at a time\n", pre));
456:     } else if (cJ == SNESComputeJacobianDefaultColor) {
457:       PetscCall(PetscViewerASCIIPrintf(viewer, "  %sJacobian is built using finite differences with coloring\n", pre));
458:       /* it slightly breaks data encapsulation for access the DMDA information directly */
459:     } else if (cJ == SNESComputeJacobian_DMDA) {
460:       MatFDColoring fdcoloring;
461:       PetscCall(PetscObjectQuery((PetscObject)dm, "DMDASNES_FDCOLORING", (PetscObject *)&fdcoloring));
462:       if (fdcoloring) {
463:         PetscCall(PetscViewerASCIIPrintf(viewer, "  %sJacobian is built using colored finite differences on a DMDA\n", pre));
464:       } else {
465:         PetscCall(PetscViewerASCIIPrintf(viewer, "  %sJacobian is built using a DMDA local Jacobian\n", pre));
466:       }
467:     } else if (snes->mf && !snes->mf_operator) {
468:       PetscCall(PetscViewerASCIIPrintf(viewer, "  Jacobian is applied matrix-free with differencing, no explicit Jacobian\n"));
469:     }
470:   } else if (isstring) {
471:     const char *type;
472:     PetscCall(SNESGetType(snes, &type));
473:     PetscCall(PetscViewerStringSPrintf(viewer, " SNESType: %-7.7s", type));
474:     PetscTryTypeMethod(snes, view, viewer);
475:   } else if (isbinary) {
476:     PetscInt    classid = SNES_FILE_CLASSID;
477:     MPI_Comm    comm;
478:     PetscMPIInt rank;
479:     char        type[256];
481:     PetscCall(PetscObjectGetComm((PetscObject)snes, &comm));
482:     PetscCallMPI(MPI_Comm_rank(comm, &rank));
483:     if (rank == 0) {
484:       PetscCall(PetscViewerBinaryWrite(viewer, &classid, 1, PETSC_INT));
485:       PetscCall(PetscStrncpy(type, ((PetscObject)snes)->type_name, sizeof(type)));
486:       PetscCall(PetscViewerBinaryWrite(viewer, type, sizeof(type), PETSC_CHAR));
487:     }
488:     PetscTryTypeMethod(snes, view, viewer);
489:   } else if (isdraw) {
490:     PetscDraw draw;
491:     char      str[36];
492:     PetscReal x, y, bottom, h;
494:     PetscCall(PetscViewerDrawGetDraw(viewer, 0, &draw));
495:     PetscCall(PetscDrawGetCurrentPoint(draw, &x, &y));
496:     PetscCall(PetscStrncpy(str, "SNES: ", sizeof(str)));
497:     PetscCall(PetscStrlcat(str, ((PetscObject)snes)->type_name, sizeof(str)));
498:     PetscCall(PetscDrawStringBoxed(draw, x, y, PETSC_DRAW_BLUE, PETSC_DRAW_BLACK, str, NULL, &h));
499:     bottom = y - h;
500:     PetscCall(PetscDrawPushCurrentPoint(draw, x, bottom));
501:     PetscTryTypeMethod(snes, view, viewer);
502: #if defined(PETSC_HAVE_SAWS)
503:   } else if (issaws) {
504:     PetscMPIInt rank;
505:     const char *name;
507:     PetscCall(PetscObjectGetName((PetscObject)snes, &name));
508:     PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
509:     if (!((PetscObject)snes)->amsmem && rank == 0) {
510:       char dir[1024];
512:       PetscCall(PetscObjectViewSAWs((PetscObject)snes, viewer));
513:       PetscCall(PetscSNPrintf(dir, 1024, "/PETSc/Objects/%s/its", name));
514:       PetscCallSAWs(SAWs_Register, (dir, &snes->iter, 1, SAWs_READ, SAWs_INT));
515:       if (!snes->conv_hist) PetscCall(SNESSetConvergenceHistory(snes, NULL, NULL, PETSC_DECIDE, PETSC_TRUE));
516:       PetscCall(PetscSNPrintf(dir, 1024, "/PETSc/Objects/%s/conv_hist", name));
517:       PetscCallSAWs(SAWs_Register, (dir, snes->conv_hist, 10, SAWs_READ, SAWs_DOUBLE));
518:     }
519: #endif
520:   }
521:   if (snes->linesearch) {
522:     PetscCall(SNESGetLineSearch(snes, &linesearch));
523:     PetscCall(PetscViewerASCIIPushTab(viewer));
524:     PetscCall(SNESLineSearchView(linesearch, viewer));
525:     PetscCall(PetscViewerASCIIPopTab(viewer));
526:   }
527:   if (snes->npc && snes->usesnpc) {
528:     PetscCall(PetscViewerASCIIPushTab(viewer));
529:     PetscCall(SNESView(snes->npc, viewer));
530:     PetscCall(PetscViewerASCIIPopTab(viewer));
531:   }
532:   PetscCall(PetscViewerASCIIPushTab(viewer));
533:   PetscCall(DMGetDMSNES(snes->dm, &dmsnes));
534:   PetscCall(DMSNESView(dmsnes, viewer));
535:   PetscCall(PetscViewerASCIIPopTab(viewer));
536:   if (snes->usesksp) {
537:     PetscCall(SNESGetKSP(snes, &ksp));
538:     PetscCall(PetscViewerASCIIPushTab(viewer));
539:     PetscCall(KSPView(ksp, viewer));
540:     PetscCall(PetscViewerASCIIPopTab(viewer));
541:   }
542:   if (isdraw) {
543:     PetscDraw draw;
544:     PetscCall(PetscViewerDrawGetDraw(viewer, 0, &draw));
545:     PetscCall(PetscDrawPopCurrentPoint(draw));
546:   }
547:   PetscFunctionReturn(PETSC_SUCCESS);
548: }
550: /*
551:   We retain a list of functions that also take SNES command
552:   line options. These are called at the end SNESSetFromOptions()
553: */
554: #define MAXSETFROMOPTIONS 5
555: static PetscInt numberofsetfromoptions;
556: static PetscErrorCode (*othersetfromoptions[MAXSETFROMOPTIONS])(SNES);
558: /*@C
559:   SNESAddOptionsChecker - Adds an additional function to check for `SNES` options.
561:   Not Collective
563:   Input Parameter:
564: . snescheck - function that checks for options
566:   Calling sequence of `snescheck`:
567: . snes - the `SNES` object for which it is checking options
569:   Level: developer
571: .seealso: [](ch_snes), `SNES`, `SNESSetFromOptions()`
572: @*/
573: PetscErrorCode SNESAddOptionsChecker(PetscErrorCode (*snescheck)(SNES snes))
574: {
575:   PetscFunctionBegin;
576:   PetscCheck(numberofsetfromoptions < MAXSETFROMOPTIONS, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Too many options checkers, only %d allowed", MAXSETFROMOPTIONS);
577:   othersetfromoptions[numberofsetfromoptions++] = snescheck;
578:   PetscFunctionReturn(PETSC_SUCCESS);
579: }
581: static PetscErrorCode SNESSetUpMatrixFree_Private(SNES snes, PetscBool hasOperator, PetscInt version)
582: {
583:   Mat          J;
584:   MatNullSpace nullsp;
586:   PetscFunctionBegin;
589:   if (!snes->vec_func && (snes->jacobian || snes->jacobian_pre)) {
590:     Mat A = snes->jacobian, B = snes->jacobian_pre;
591:     PetscCall(MatCreateVecs(A ? A : B, NULL, &snes->vec_func));
592:   }
594:   PetscCheck(version == 1 || version == 2, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "matrix-free operator routines, only version 1 and 2");
595:   if (version == 1) {
596:     PetscCall(MatCreateSNESMF(snes, &J));
597:     PetscCall(MatMFFDSetOptionsPrefix(J, ((PetscObject)snes)->prefix));
598:     PetscCall(MatSetFromOptions(J));
599:     /* TODO: the version 2 code should be merged into the MatCreateSNESMF() and MatCreateMFFD() infrastructure and then removed */
600:   } else /* if (version == 2) */ {
601:     PetscCheck(snes->vec_func, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "SNESSetFunction() must be called first");
602: #if !defined(PETSC_USE_COMPLEX) && !defined(PETSC_USE_REAL_SINGLE) && !defined(PETSC_USE_REAL___FLOAT128) && !defined(PETSC_USE_REAL___FP16)
603:     PetscCall(MatCreateSNESMFMore(snes, snes->vec_func, &J));
604: #else
605:     SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SUP, "matrix-free operator routines (version 2)");
606: #endif
607:   }
609:   /* attach any user provided null space that was on Amat to the newly created matrix-free matrix */
610:   if (snes->jacobian) {
611:     PetscCall(MatGetNullSpace(snes->jacobian, &nullsp));
612:     if (nullsp) PetscCall(MatSetNullSpace(J, nullsp));
613:   }
615:   PetscCall(PetscInfo(snes, "Setting default matrix-free operator routines (version %" PetscInt_FMT ")\n", version));
616:   if (hasOperator) {
617:     /* This version replaces the user provided Jacobian matrix with a
618:        matrix-free version but still employs the user-provided preconditioner matrix. */
619:     PetscCall(SNESSetJacobian(snes, J, NULL, NULL, NULL));
620:   } else {
621:     /* This version replaces both the user-provided Jacobian and the user-
622:      provided preconditioner Jacobian with the default matrix-free version. */
623:     if (snes->npcside == PC_LEFT && snes->npc) {
624:       if (!snes->jacobian) PetscCall(SNESSetJacobian(snes, J, NULL, NULL, NULL));
625:     } else {
626:       KSP       ksp;
627:       PC        pc;
628:       PetscBool match;
630:       PetscCall(SNESSetJacobian(snes, J, J, MatMFFDComputeJacobian, NULL));
631:       /* Force no preconditioner */
632:       PetscCall(SNESGetKSP(snes, &ksp));
633:       PetscCall(KSPGetPC(ksp, &pc));
634:       PetscCall(PetscObjectTypeCompareAny((PetscObject)pc, &match, PCSHELL, PCH2OPUS, ""));
635:       if (!match) {
636:         PetscCall(PetscInfo(snes, "Setting default matrix-free preconditioner routines\nThat is no preconditioner is being used\n"));
637:         PetscCall(PCSetType(pc, PCNONE));
638:       }
639:     }
640:   }
641:   PetscCall(MatDestroy(&J));
642:   PetscFunctionReturn(PETSC_SUCCESS);
643: }
645: static PetscErrorCode DMRestrictHook_SNESVecSol(DM dmfine, Mat Restrict, Vec Rscale, Mat Inject, DM dmcoarse, void *ctx)
646: {
647:   SNES snes = (SNES)ctx;
648:   Vec  Xfine, Xfine_named = NULL, Xcoarse;
650:   PetscFunctionBegin;
651:   if (PetscLogPrintInfo) {
652:     PetscInt finelevel, coarselevel, fineclevel, coarseclevel;
653:     PetscCall(DMGetRefineLevel(dmfine, &finelevel));
654:     PetscCall(DMGetCoarsenLevel(dmfine, &fineclevel));
655:     PetscCall(DMGetRefineLevel(dmcoarse, &coarselevel));
656:     PetscCall(DMGetCoarsenLevel(dmcoarse, &coarseclevel));
657:     PetscCall(PetscInfo(dmfine, "Restricting SNES solution vector from level %" PetscInt_FMT "-%" PetscInt_FMT " to level %" PetscInt_FMT "-%" PetscInt_FMT "\n", finelevel, fineclevel, coarselevel, coarseclevel));
658:   }
659:   if (dmfine == snes->dm) Xfine = snes->vec_sol;
660:   else {
661:     PetscCall(DMGetNamedGlobalVector(dmfine, "SNESVecSol", &Xfine_named));
662:     Xfine = Xfine_named;
663:   }
664:   PetscCall(DMGetNamedGlobalVector(dmcoarse, "SNESVecSol", &Xcoarse));
665:   if (Inject) {
666:     PetscCall(MatRestrict(Inject, Xfine, Xcoarse));
667:   } else {
668:     PetscCall(MatRestrict(Restrict, Xfine, Xcoarse));
669:     PetscCall(VecPointwiseMult(Xcoarse, Xcoarse, Rscale));
670:   }
671:   PetscCall(DMRestoreNamedGlobalVector(dmcoarse, "SNESVecSol", &Xcoarse));
672:   if (Xfine_named) PetscCall(DMRestoreNamedGlobalVector(dmfine, "SNESVecSol", &Xfine_named));
673:   PetscFunctionReturn(PETSC_SUCCESS);
674: }
676: static PetscErrorCode DMCoarsenHook_SNESVecSol(DM dm, DM dmc, void *ctx)
677: {
678:   PetscFunctionBegin;
679:   PetscCall(DMCoarsenHookAdd(dmc, DMCoarsenHook_SNESVecSol, DMRestrictHook_SNESVecSol, ctx));
680:   PetscFunctionReturn(PETSC_SUCCESS);
681: }
683: /* This may be called to rediscretize the operator on levels of linear multigrid. The DM shuffle is so the user can
684:  * safely call SNESGetDM() in their residual evaluation routine. */
685: static PetscErrorCode KSPComputeOperators_SNES(KSP ksp, Mat A, Mat B, void *ctx)
686: {
687:   SNES            snes = (SNES)ctx;
688:   DMSNES          sdm;
689:   Vec             X, Xnamed = NULL;
690:   DM              dmsave;
691:   void           *ctxsave;
692:   SNESJacobianFn *jac = NULL;
694:   PetscFunctionBegin;
695:   dmsave = snes->dm;
696:   PetscCall(KSPGetDM(ksp, &snes->dm));
697:   if (dmsave == snes->dm) X = snes->vec_sol; /* We are on the finest level */
698:   else {
699:     PetscBool has;
701:     /* We are on a coarser level, this vec was initialized using a DM restrict hook */
702:     PetscCall(DMHasNamedGlobalVector(snes->dm, "SNESVecSol", &has));
703:     PetscCheck(has, PetscObjectComm((PetscObject)snes->dm), PETSC_ERR_PLIB, "Missing SNESVecSol");
704:     PetscCall(DMGetNamedGlobalVector(snes->dm, "SNESVecSol", &Xnamed));
705:     X = Xnamed;
706:     PetscCall(SNESGetJacobian(snes, NULL, NULL, &jac, &ctxsave));
707:     /* If the DM's don't match up, the MatFDColoring context needed for the jacobian won't match up either -- fixit. */
708:     if (jac == SNESComputeJacobianDefaultColor) PetscCall(SNESSetJacobian(snes, NULL, NULL, SNESComputeJacobianDefaultColor, NULL));
709:   }
711:   /* Compute the operators */
712:   PetscCall(DMGetDMSNES(snes->dm, &sdm));
713:   if (Xnamed && sdm->ops->computefunction) {
714:     /* The SNES contract with the user is that ComputeFunction is always called before ComputeJacobian.
715:        We make sure of this here. Disable affine shift since it is for the finest level */
716:     Vec F, saverhs = snes->vec_rhs;
718:     snes->vec_rhs = NULL;
719:     PetscCall(DMGetGlobalVector(snes->dm, &F));
720:     PetscCall(SNESComputeFunction(snes, X, F));
721:     PetscCall(DMRestoreGlobalVector(snes->dm, &F));
722:     snes->vec_rhs = saverhs;
723:     snes->nfuncs--; /* Do not log coarser level evaluations */
724:   }
725:   /* Make sure KSP DM has the Jacobian computation routine */
726:   if (!sdm->ops->computejacobian) PetscCall(DMCopyDMSNES(dmsave, snes->dm));
727:   PetscCall(SNESComputeJacobian(snes, X, A, B));
729:   /* Put the previous context back */
730:   if (snes->dm != dmsave && jac == SNESComputeJacobianDefaultColor) PetscCall(SNESSetJacobian(snes, NULL, NULL, jac, ctxsave));
732:   if (Xnamed) PetscCall(DMRestoreNamedGlobalVector(snes->dm, "SNESVecSol", &Xnamed));
733:   snes->dm = dmsave;
734:   PetscFunctionReturn(PETSC_SUCCESS);
735: }
737: /*@
738:   SNESSetUpMatrices - ensures that matrices are available for `SNES` Newton-like methods, this is called by `SNESSetUp_XXX()`
740:   Collective
742:   Input Parameter:
743: . snes - `SNES` object to configure
745:   Level: developer
747:   Note:
748:   If the matrices do not yet exist it attempts to create them based on options previously set for the `SNES` such as `-snes_mf`
750:   Developer Note:
751:   The functionality of this routine overlaps in a confusing way with the functionality of `SNESSetUpMatrixFree_Private()` which is called by
752:   `SNESSetUp()` but sometimes `SNESSetUpMatrices()` is called without `SNESSetUp()` being called. A refactorization to simplify the
753:   logic that handles the matrix-free case is desirable.
755: .seealso: [](ch_snes), `SNES`, `SNESSetUp()`
756: @*/
757: PetscErrorCode SNESSetUpMatrices(SNES snes)
758: {
759:   DM     dm;
760:   DMSNES sdm;
762:   PetscFunctionBegin;
763:   PetscCall(SNESGetDM(snes, &dm));
764:   PetscCall(DMGetDMSNES(dm, &sdm));
765:   if (!snes->jacobian && snes->mf && !snes->mf_operator && !snes->jacobian_pre) {
766:     Mat   J;
767:     void *functx;
768:     PetscCall(MatCreateSNESMF(snes, &J));
769:     PetscCall(MatMFFDSetOptionsPrefix(J, ((PetscObject)snes)->prefix));
770:     PetscCall(MatSetFromOptions(J));
771:     PetscCall(SNESGetFunction(snes, NULL, NULL, &functx));
772:     PetscCall(SNESSetJacobian(snes, J, J, NULL, NULL));
773:     PetscCall(MatDestroy(&J));
774:   } else if (snes->mf_operator && !snes->jacobian_pre && !snes->jacobian) {
775:     Mat J, B;
776:     PetscCall(MatCreateSNESMF(snes, &J));
777:     PetscCall(MatMFFDSetOptionsPrefix(J, ((PetscObject)snes)->prefix));
778:     PetscCall(MatSetFromOptions(J));
779:     PetscCall(DMCreateMatrix(snes->dm, &B));
780:     /* sdm->computejacobian was already set to reach here */
781:     PetscCall(SNESSetJacobian(snes, J, B, NULL, NULL));
782:     PetscCall(MatDestroy(&J));
783:     PetscCall(MatDestroy(&B));
784:   } else if (!snes->jacobian_pre) {
785:     PetscDS   prob;
786:     Mat       J, B;
787:     PetscBool hasPrec = PETSC_FALSE;
789:     J = snes->jacobian;
790:     PetscCall(DMGetDS(dm, &prob));
791:     if (prob) PetscCall(PetscDSHasJacobianPreconditioner(prob, &hasPrec));
792:     if (J) PetscCall(PetscObjectReference((PetscObject)J));
793:     else if (hasPrec) PetscCall(DMCreateMatrix(snes->dm, &J));
794:     PetscCall(DMCreateMatrix(snes->dm, &B));
795:     PetscCall(SNESSetJacobian(snes, J ? J : B, B, NULL, NULL));
796:     PetscCall(MatDestroy(&J));
797:     PetscCall(MatDestroy(&B));
798:   }
799:   {
800:     KSP ksp;
801:     PetscCall(SNESGetKSP(snes, &ksp));
802:     PetscCall(KSPSetComputeOperators(ksp, KSPComputeOperators_SNES, snes));
803:     PetscCall(DMCoarsenHookAdd(snes->dm, DMCoarsenHook_SNESVecSol, DMRestrictHook_SNESVecSol, snes));
804:   }
805:   PetscFunctionReturn(PETSC_SUCCESS);
806: }
808: static PetscErrorCode SNESMonitorPauseFinal_Internal(SNES snes)
809: {
810:   PetscInt i;
812:   PetscFunctionBegin;
813:   if (!snes->pauseFinal) PetscFunctionReturn(PETSC_SUCCESS);
814:   for (i = 0; i < snes->numbermonitors; ++i) {
815:     PetscViewerAndFormat *vf = (PetscViewerAndFormat *)snes->monitorcontext[i];
816:     PetscDraw             draw;
817:     PetscReal             lpause;
819:     if (!vf) continue;
820:     if (vf->lg) {
821:       if (!PetscCheckPointer(vf->lg, PETSC_OBJECT)) continue;
822:       if (((PetscObject)vf->lg)->classid != PETSC_DRAWLG_CLASSID) continue;
823:       PetscCall(PetscDrawLGGetDraw(vf->lg, &draw));
824:       PetscCall(PetscDrawGetPause(draw, &lpause));
825:       PetscCall(PetscDrawSetPause(draw, -1.0));
826:       PetscCall(PetscDrawPause(draw));
827:       PetscCall(PetscDrawSetPause(draw, lpause));
828:     } else {
829:       PetscBool isdraw;
831:       if (!PetscCheckPointer(vf->viewer, PETSC_OBJECT)) continue;
832:       if (((PetscObject)vf->viewer)->classid != PETSC_VIEWER_CLASSID) continue;
833:       PetscCall(PetscObjectTypeCompare((PetscObject)vf->viewer, PETSCVIEWERDRAW, &isdraw));
834:       if (!isdraw) continue;
835:       PetscCall(PetscViewerDrawGetDraw(vf->viewer, 0, &draw));
836:       PetscCall(PetscDrawGetPause(draw, &lpause));
837:       PetscCall(PetscDrawSetPause(draw, -1.0));
838:       PetscCall(PetscDrawPause(draw));
839:       PetscCall(PetscDrawSetPause(draw, lpause));
840:     }
841:   }
842:   PetscFunctionReturn(PETSC_SUCCESS);
843: }
845: /*@C
846:   SNESMonitorSetFromOptions - Sets a monitor function and viewer appropriate for the type indicated by the user
848:   Collective
850:   Input Parameters:
851: + snes         - `SNES` object you wish to monitor
852: . name         - the monitor type one is seeking
853: . help         - message indicating what monitoring is done
854: . manual       - manual page for the monitor
855: . monitor      - the monitor function
856: - monitorsetup - a function that is called once ONLY if the user selected this monitor that may set additional features of the `SNES` or `PetscViewer` objects
858:   Calling sequence of `monitor`:
859: + snes - the nonlinear solver context
860: . it   - the current iteration
861: . r    - the current function norm
862: - vf   - a `PetscViewerAndFormat` struct that contains the `PetscViewer` and `PetscViewerFormat` to use
864:   Calling sequence of `monitorsetup`:
865: + snes - the nonlinear solver context
866: - vf   - a `PetscViewerAndFormat` struct that contains the `PetscViewer` and `PetscViewerFormat` to use
868:   Options Database Key:
869: . -name - trigger the use of this monitor in `SNESSetFromOptions()`
871:   Level: advanced
873: .seealso: [](ch_snes), `PetscOptionsCreateViewer()`, `PetscOptionsGetReal()`, `PetscOptionsHasName()`, `PetscOptionsGetString()`,
874:           `PetscOptionsGetIntArray()`, `PetscOptionsGetRealArray()`, `PetscOptionsBool()`
875:           `PetscOptionsInt()`, `PetscOptionsString()`, `PetscOptionsReal()`,
876:           `PetscOptionsName()`, `PetscOptionsBegin()`, `PetscOptionsEnd()`, `PetscOptionsHeadBegin()`,
877:           `PetscOptionsStringArray()`, `PetscOptionsRealArray()`, `PetscOptionsScalar()`,
878:           `PetscOptionsBoolGroupBegin()`, `PetscOptionsBoolGroup()`, `PetscOptionsBoolGroupEnd()`,
879:           `PetscOptionsFList()`, `PetscOptionsEList()`
880: @*/
881: PetscErrorCode SNESMonitorSetFromOptions(SNES snes, const char name[], const char help[], const char manual[], PetscErrorCode (*monitor)(SNES snes, PetscInt it, PetscReal r, PetscViewerAndFormat *vf), PetscErrorCode (*monitorsetup)(SNES snes, PetscViewerAndFormat *vf))
882: {
883:   PetscViewer       viewer;
884:   PetscViewerFormat format;
885:   PetscBool         flg;
887:   PetscFunctionBegin;
888:   PetscCall(PetscOptionsCreateViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, name, &viewer, &format, &flg));
889:   if (flg) {
890:     PetscViewerAndFormat *vf;
891:     PetscCall(PetscViewerAndFormatCreate(viewer, format, &vf));
892:     PetscCall(PetscViewerDestroy(&viewer));
893:     if (monitorsetup) PetscCall((*monitorsetup)(snes, vf));
894:     PetscCall(SNESMonitorSet(snes, (PetscErrorCode (*)(SNES, PetscInt, PetscReal, void *))monitor, vf, (PetscErrorCode (*)(void **))PetscViewerAndFormatDestroy));
895:   }
896:   PetscFunctionReturn(PETSC_SUCCESS);
897: }
899: PetscErrorCode SNESEWSetFromOptions_Private(SNESKSPEW *kctx, PetscBool print_api, MPI_Comm comm, const char *prefix)
900: {
901:   const char *api = print_api ? "SNESKSPSetParametersEW" : NULL;
903:   PetscFunctionBegin;
904:   PetscOptionsBegin(comm, prefix, "Eisenstat and Walker type forcing options", "KSP");
905:   PetscCall(PetscOptionsInt("-ksp_ew_version", "Version 1, 2 or 3", api, kctx->version, &kctx->version, NULL));
906:   PetscCall(PetscOptionsReal("-ksp_ew_rtol0", "0 <= rtol0 < 1", api, kctx->rtol_0, &kctx->rtol_0, NULL));
907:   kctx->rtol_max = PetscMax(kctx->rtol_0, kctx->rtol_max);
908:   PetscCall(PetscOptionsReal("-ksp_ew_rtolmax", "0 <= rtolmax < 1", api, kctx->rtol_max, &kctx->rtol_max, NULL));
909:   PetscCall(PetscOptionsReal("-ksp_ew_gamma", "0 <= gamma <= 1", api, kctx->gamma, &kctx->gamma, NULL));
910:   PetscCall(PetscOptionsReal("-ksp_ew_alpha", "1 < alpha <= 2", api, kctx->alpha, &kctx->alpha, NULL));
911:   PetscCall(PetscOptionsReal("-ksp_ew_alpha2", "alpha2", NULL, kctx->alpha2, &kctx->alpha2, NULL));
912:   PetscCall(PetscOptionsReal("-ksp_ew_threshold", "0 < threshold < 1", api, kctx->threshold, &kctx->threshold, NULL));
913:   PetscCall(PetscOptionsReal("-ksp_ew_v4_p1", "p1", NULL, kctx->v4_p1, &kctx->v4_p1, NULL));
914:   PetscCall(PetscOptionsReal("-ksp_ew_v4_p2", "p2", NULL, kctx->v4_p2, &kctx->v4_p2, NULL));
915:   PetscCall(PetscOptionsReal("-ksp_ew_v4_p3", "p3", NULL, kctx->v4_p3, &kctx->v4_p3, NULL));
916:   PetscCall(PetscOptionsReal("-ksp_ew_v4_m1", "Scaling when rk-1 in [p2,p3)", NULL, kctx->v4_m1, &kctx->v4_m1, NULL));
917:   PetscCall(PetscOptionsReal("-ksp_ew_v4_m2", "Scaling when rk-1 in [p3,+infty)", NULL, kctx->v4_m2, &kctx->v4_m2, NULL));
918:   PetscCall(PetscOptionsReal("-ksp_ew_v4_m3", "Threshold for successive rtol (0.1 in Eq.7)", NULL, kctx->v4_m3, &kctx->v4_m3, NULL));
919:   PetscCall(PetscOptionsReal("-ksp_ew_v4_m4", "Adaptation scaling (0.5 in Eq.7)", NULL, kctx->v4_m4, &kctx->v4_m4, NULL));
920:   PetscOptionsEnd();
921:   PetscFunctionReturn(PETSC_SUCCESS);
922: }
924: /*@
925:   SNESSetFromOptions - Sets various `SNES` and `KSP` parameters from user options.
927:   Collective
929:   Input Parameter:
930: . snes - the `SNES` context
932:   Options Database Keys:
933: + -snes_type <type>                                                            - newtonls, newtontr, ngmres, ncg, nrichardson, qn, vi, fas, `SNESType` for complete list
934: . -snes_rtol <rtol>                                                            - relative decrease in tolerance norm from initial
935: . -snes_atol <abstol>                                                          - absolute tolerance of residual norm
936: . -snes_stol <stol>                                                            - convergence tolerance in terms of the norm of the change in the solution between steps
937: . -snes_divergence_tolerance <divtol>                                          - if the residual goes above divtol*rnorm0, exit with divergence
938: . -snes_max_it <max_it>                                                        - maximum number of iterations
939: . -snes_max_funcs <max_funcs>                                                  - maximum number of function evaluations
940: . -snes_force_iteration <force>                                                - force `SNESSolve()` to take at least one iteration
941: . -snes_max_fail <max_fail>                                                    - maximum number of line search failures allowed before stopping, default is none
942: . -snes_max_linear_solve_fail                                                  - number of linear solver failures before SNESSolve() stops
943: . -snes_lag_preconditioner <lag>                                               - how often preconditioner is rebuilt (use -1 to never rebuild)
944: . -snes_lag_preconditioner_persists <true,false>                               - retains the -snes_lag_preconditioner information across multiple SNESSolve()
945: . -snes_lag_jacobian <lag>                                                     - how often Jacobian is rebuilt (use -1 to never rebuild)
946: . -snes_lag_jacobian_persists <true,false>                                     - retains the -snes_lag_jacobian information across multiple SNESSolve()
947: . -snes_convergence_test <default,skip,correct_pressure>                       - convergence test in nonlinear solver. default `SNESConvergedDefault()`. skip `SNESConvergedSkip()` means continue iterating until max_it or some other criterion is reached, saving expense of convergence test. correct_pressure `SNESConvergedCorrectPressure()` has special handling of a pressure null space.
948: . -snes_monitor [ascii][:filename][:viewer format]                             - prints residual norm at each iteration. if no filename given prints to stdout
949: . -snes_monitor_solution [ascii binary draw][:filename][:viewer format]        - plots solution at each iteration
950: . -snes_monitor_residual [ascii binary draw][:filename][:viewer format]        - plots residual (not its norm) at each iteration
951: . -snes_monitor_solution_update [ascii binary draw][:filename][:viewer format] - plots update to solution at each iteration
952: . -snes_monitor_lg_residualnorm                                                - plots residual norm at each iteration
953: . -snes_monitor_lg_range                                                       - plots residual norm at each iteration
954: . -snes_monitor_pause_final                                                    - Pauses all monitor drawing after the solver ends
955: . -snes_fd                                                                     - use finite differences to compute Jacobian; very slow, only for testing
956: . -snes_fd_color                                                               - use finite differences with coloring to compute Jacobian
957: . -snes_mf_ksp_monitor                                                         - if using matrix-free multiply then print h at each `KSP` iteration
958: . -snes_converged_reason                                                       - print the reason for convergence/divergence after each solve
959: . -npc_snes_type <type>                                                        - the `SNES` type to use as a nonlinear preconditioner
960: . -snes_test_jacobian <optional threshold>                                     - compare the user provided Jacobian with one computed via finite differences to check for errors.  If a threshold is given, display only those entries whose difference is greater than the threshold.
961: - -snes_test_jacobian_view                                                     - display the user provided Jacobian, the finite difference Jacobian and the difference between them to help users detect the location of errors in the user provided Jacobian.
963:   Options Database Keys for Eisenstat-Walker method:
964: + -snes_ksp_ew                       - use Eisenstat-Walker method for determining linear system convergence
965: . -snes_ksp_ew_version ver           - version of  Eisenstat-Walker method
966: . -snes_ksp_ew_rtol0 <rtol0>         - Sets rtol0
967: . -snes_ksp_ew_rtolmax <rtolmax>     - Sets rtolmax
968: . -snes_ksp_ew_gamma <gamma>         - Sets gamma
969: . -snes_ksp_ew_alpha <alpha>         - Sets alpha
970: . -snes_ksp_ew_alpha2 <alpha2>       - Sets alpha2
971: - -snes_ksp_ew_threshold <threshold> - Sets threshold
973:   Level: beginner
975:   Notes:
976:   To see all options, run your program with the -help option or consult the users manual
978:   `SNES` supports three approaches for computing (approximate) Jacobians: user provided via `SNESSetJacobian()`, matrix-free using `MatCreateSNESMF()`,
979:   and computing explicitly with
980:   finite differences and coloring using `MatFDColoring`. It is also possible to use automatic differentiation and the `MatFDColoring` object.
982: .seealso: [](ch_snes), `SNESType`, `SNESSetOptionsPrefix()`, `SNESResetFromOptions()`, `SNES`, `SNESCreate()`, `MatCreateSNESMF()`, `MatFDColoring`
983: @*/
984: PetscErrorCode SNESSetFromOptions(SNES snes)
985: {
986:   PetscBool   flg, pcset, persist, set;
987:   PetscInt    i, indx, lag, grids, max_its, max_funcs;
988:   const char *deft        = SNESNEWTONLS;
989:   const char *convtests[] = {"default", "skip", "correct_pressure"};
990:   SNESKSPEW  *kctx        = NULL;
991:   char        type[256], monfilename[PETSC_MAX_PATH_LEN], ewprefix[256];
992:   PCSide      pcside;
993:   const char *optionsprefix;
994:   PetscReal   rtol, abstol, stol;
996:   PetscFunctionBegin;
998:   PetscCall(SNESRegisterAll());
999:   PetscObjectOptionsBegin((PetscObject)snes);
1000:   if (((PetscObject)snes)->type_name) deft = ((PetscObject)snes)->type_name;
1001:   PetscCall(PetscOptionsFList("-snes_type", "Nonlinear solver method", "SNESSetType", SNESList, deft, type, 256, &flg));
1002:   if (flg) {
1003:     PetscCall(SNESSetType(snes, type));
1004:   } else if (!((PetscObject)snes)->type_name) {
1005:     PetscCall(SNESSetType(snes, deft));
1006:   }
1008:   abstol    = snes->abstol;
1009:   rtol      = snes->rtol;
1010:   stol      = snes->stol;
1011:   max_its   = snes->max_its;
1012:   max_funcs = snes->max_funcs;
1013:   PetscCall(PetscOptionsReal("-snes_rtol", "Stop if decrease in function norm less than", "SNESSetTolerances", snes->rtol, &rtol, NULL));
1014:   PetscCall(PetscOptionsReal("-snes_atol", "Stop if function norm less than", "SNESSetTolerances", snes->abstol, &abstol, NULL));
1015:   PetscCall(PetscOptionsReal("-snes_stol", "Stop if step length less than", "SNESSetTolerances", snes->stol, &stol, NULL));
1016:   PetscCall(PetscOptionsInt("-snes_max_it", "Maximum iterations", "SNESSetTolerances", snes->max_its, &max_its, NULL));
1017:   PetscCall(PetscOptionsInt("-snes_max_funcs", "Maximum function evaluations", "SNESSetTolerances", snes->max_funcs, &max_funcs, NULL));
1018:   PetscCall(SNESSetTolerances(snes, abstol, rtol, stol, max_its, max_funcs));
1020:   PetscCall(PetscOptionsReal("-snes_divergence_tolerance", "Stop if residual norm increases by this factor", "SNESSetDivergenceTolerance", snes->divtol, &snes->divtol, &flg));
1021:   if (flg) PetscCall(SNESSetDivergenceTolerance(snes, snes->divtol));
1023:   PetscCall(PetscOptionsInt("-snes_max_fail", "Maximum nonlinear step failures", "SNESSetMaxNonlinearStepFailures", snes->maxFailures, &snes->maxFailures, &flg));
1024:   if (flg) PetscCall(SNESSetMaxNonlinearStepFailures(snes, snes->maxFailures));
1026:   PetscCall(PetscOptionsInt("-snes_max_linear_solve_fail", "Maximum failures in linear solves allowed", "SNESSetMaxLinearSolveFailures", snes->maxLinearSolveFailures, &snes->maxLinearSolveFailures, &flg));
1027:   if (flg) PetscCall(SNESSetMaxLinearSolveFailures(snes, snes->maxLinearSolveFailures));
1029:   PetscCall(PetscOptionsBool("-snes_error_if_not_converged", "Generate error if solver does not converge", "SNESSetErrorIfNotConverged", snes->errorifnotconverged, &snes->errorifnotconverged, NULL));
1030:   PetscCall(PetscOptionsBool("-snes_force_iteration", "Force SNESSolve() to take at least one iteration", "SNESSetForceIteration", snes->forceiteration, &snes->forceiteration, NULL));
1031:   PetscCall(PetscOptionsBool("-snes_check_jacobian_domain_error", "Check Jacobian domain error after Jacobian evaluation", "SNESCheckJacobianDomainError", snes->checkjacdomainerror, &snes->checkjacdomainerror, NULL));
1033:   PetscCall(PetscOptionsInt("-snes_lag_preconditioner", "How often to rebuild preconditioner", "SNESSetLagPreconditioner", snes->lagpreconditioner, &lag, &flg));
1034:   if (flg) {
1035:     PetscCheck(lag != -1, PetscObjectComm((PetscObject)snes), PETSC_ERR_USER, "Cannot set the lag to -1 from the command line since the preconditioner must be built as least once, perhaps you mean -2");
1036:     PetscCall(SNESSetLagPreconditioner(snes, lag));
1037:   }
1038:   PetscCall(PetscOptionsBool("-snes_lag_preconditioner_persists", "Preconditioner lagging through multiple SNES solves", "SNESSetLagPreconditionerPersists", snes->lagjac_persist, &persist, &flg));
1039:   if (flg) PetscCall(SNESSetLagPreconditionerPersists(snes, persist));
1040:   PetscCall(PetscOptionsInt("-snes_lag_jacobian", "How often to rebuild Jacobian", "SNESSetLagJacobian", snes->lagjacobian, &lag, &flg));
1041:   if (flg) {
1042:     PetscCheck(lag != -1, PetscObjectComm((PetscObject)snes), PETSC_ERR_USER, "Cannot set the lag to -1 from the command line since the Jacobian must be built as least once, perhaps you mean -2");
1043:     PetscCall(SNESSetLagJacobian(snes, lag));
1044:   }
1045:   PetscCall(PetscOptionsBool("-snes_lag_jacobian_persists", "Jacobian lagging through multiple SNES solves", "SNESSetLagJacobianPersists", snes->lagjac_persist, &persist, &flg));
1046:   if (flg) PetscCall(SNESSetLagJacobianPersists(snes, persist));
1048:   PetscCall(PetscOptionsInt("-snes_grid_sequence", "Use grid sequencing to generate initial guess", "SNESSetGridSequence", snes->gridsequence, &grids, &flg));
1049:   if (flg) PetscCall(SNESSetGridSequence(snes, grids));
1051:   PetscCall(PetscOptionsEList("-snes_convergence_test", "Convergence test", "SNESSetConvergenceTest", convtests, PETSC_STATIC_ARRAY_LENGTH(convtests), "default", &indx, &flg));
1052:   if (flg) {
1053:     switch (indx) {
1054:     case 0:
1055:       PetscCall(SNESSetConvergenceTest(snes, SNESConvergedDefault, NULL, NULL));
1056:       break;
1057:     case 1:
1058:       PetscCall(SNESSetConvergenceTest(snes, SNESConvergedSkip, NULL, NULL));
1059:       break;
1060:     case 2:
1061:       PetscCall(SNESSetConvergenceTest(snes, SNESConvergedCorrectPressure, NULL, NULL));
1062:       break;
1063:     }
1064:   }
1066:   PetscCall(PetscOptionsEList("-snes_norm_schedule", "SNES Norm schedule", "SNESSetNormSchedule", SNESNormSchedules, 5, "function", &indx, &flg));
1067:   if (flg) PetscCall(SNESSetNormSchedule(snes, (SNESNormSchedule)indx));
1069:   PetscCall(PetscOptionsEList("-snes_function_type", "SNES Norm schedule", "SNESSetFunctionType", SNESFunctionTypes, 2, "unpreconditioned", &indx, &flg));
1070:   if (flg) PetscCall(SNESSetFunctionType(snes, (SNESFunctionType)indx));
1072:   kctx = (SNESKSPEW *)snes->kspconvctx;
1074:   PetscCall(PetscOptionsBool("-snes_ksp_ew", "Use Eisentat-Walker linear system convergence test", "SNESKSPSetUseEW", snes->ksp_ewconv, &snes->ksp_ewconv, NULL));
1076:   PetscCall(SNESGetOptionsPrefix(snes, &optionsprefix));
1077:   PetscCall(PetscSNPrintf(ewprefix, sizeof(ewprefix), "%s%s", optionsprefix ? optionsprefix : "", "snes_"));
1078:   PetscCall(SNESEWSetFromOptions_Private(kctx, PETSC_TRUE, PetscObjectComm((PetscObject)snes), ewprefix));
1080:   flg = PETSC_FALSE;
1081:   PetscCall(PetscOptionsBool("-snes_monitor_cancel", "Remove all monitors", "SNESMonitorCancel", flg, &flg, &set));
1082:   if (set && flg) PetscCall(SNESMonitorCancel(snes));
1084:   PetscCall(SNESMonitorSetFromOptions(snes, "-snes_monitor", "Monitor norm of function", "SNESMonitorDefault", SNESMonitorDefault, SNESMonitorDefaultSetUp));
1085:   PetscCall(SNESMonitorSetFromOptions(snes, "-snes_monitor_short", "Monitor norm of function with fewer digits", "SNESMonitorDefaultShort", SNESMonitorDefaultShort, NULL));
1086:   PetscCall(SNESMonitorSetFromOptions(snes, "-snes_monitor_range", "Monitor range of elements of function", "SNESMonitorRange", SNESMonitorRange, NULL));
1088:   PetscCall(SNESMonitorSetFromOptions(snes, "-snes_monitor_ratio", "Monitor ratios of the norm of function for consecutive steps", "SNESMonitorRatio", SNESMonitorRatio, SNESMonitorRatioSetUp));
1089:   PetscCall(SNESMonitorSetFromOptions(snes, "-snes_monitor_field", "Monitor norm of function (split into fields)", "SNESMonitorDefaultField", SNESMonitorDefaultField, NULL));
1090:   PetscCall(SNESMonitorSetFromOptions(snes, "-snes_monitor_solution", "View solution at each iteration", "SNESMonitorSolution", SNESMonitorSolution, NULL));
1091:   PetscCall(SNESMonitorSetFromOptions(snes, "-snes_monitor_solution_update", "View correction at each iteration", "SNESMonitorSolutionUpdate", SNESMonitorSolutionUpdate, NULL));
1092:   PetscCall(SNESMonitorSetFromOptions(snes, "-snes_monitor_residual", "View residual at each iteration", "SNESMonitorResidual", SNESMonitorResidual, NULL));
1093:   PetscCall(SNESMonitorSetFromOptions(snes, "-snes_monitor_jacupdate_spectrum", "Print the change in the spectrum of the Jacobian", "SNESMonitorJacUpdateSpectrum", SNESMonitorJacUpdateSpectrum, NULL));
1094:   PetscCall(SNESMonitorSetFromOptions(snes, "-snes_monitor_fields", "Monitor norm of function per field", "SNESMonitorSet", SNESMonitorFields, NULL));
1095:   PetscCall(PetscOptionsBool("-snes_monitor_pause_final", "Pauses all draw monitors at the final iterate", "SNESMonitorPauseFinal_Internal", PETSC_FALSE, &snes->pauseFinal, NULL));
1097:   PetscCall(PetscOptionsString("-snes_monitor_python", "Use Python function", "SNESMonitorSet", NULL, monfilename, sizeof(monfilename), &flg));
1098:   if (flg) PetscCall(PetscPythonMonitorSet((PetscObject)snes, monfilename));
1100:   flg = PETSC_FALSE;
1101:   PetscCall(PetscOptionsBool("-snes_monitor_lg_range", "Plot function range at each iteration", "SNESMonitorLGRange", flg, &flg, NULL));
1102:   if (flg) {
1103:     PetscViewer ctx;
1105:     PetscCall(PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes), NULL, NULL, PETSC_DECIDE, PETSC_DECIDE, 400, 300, &ctx));
1106:     PetscCall(SNESMonitorSet(snes, SNESMonitorLGRange, ctx, (PetscErrorCode (*)(void **))PetscViewerDestroy));
1107:   }
1109:   PetscCall(PetscViewerDestroy(&snes->convergedreasonviewer));
1110:   PetscCall(PetscOptionsCreateViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_converged_reason", &snes->convergedreasonviewer, &snes->convergedreasonformat, NULL));
1111:   flg = PETSC_FALSE;
1112:   PetscCall(PetscOptionsBool("-snes_converged_reason_view_cancel", "Remove all converged reason viewers", "SNESConvergedReasonViewCancel", flg, &flg, &set));
1113:   if (set && flg) PetscCall(SNESConvergedReasonViewCancel(snes));
1115:   flg = PETSC_FALSE;
1116:   PetscCall(PetscOptionsBool("-snes_fd", "Use finite differences (slow) to compute Jacobian", "SNESComputeJacobianDefault", flg, &flg, NULL));
1117:   if (flg) {
1118:     void *functx;
1119:     DM    dm;
1120:     PetscCall(SNESGetDM(snes, &dm));
1121:     PetscCall(DMSNESUnsetJacobianContext_Internal(dm));
1122:     PetscCall(SNESGetFunction(snes, NULL, NULL, &functx));
1123:     PetscCall(SNESSetJacobian(snes, snes->jacobian, snes->jacobian_pre, SNESComputeJacobianDefault, functx));
1124:     PetscCall(PetscInfo(snes, "Setting default finite difference Jacobian matrix\n"));
1125:   }
1127:   flg = PETSC_FALSE;
1128:   PetscCall(PetscOptionsBool("-snes_fd_function", "Use finite differences (slow) to compute function from user objective", "SNESObjectiveComputeFunctionDefaultFD", flg, &flg, NULL));
1129:   if (flg) PetscCall(SNESSetFunction(snes, NULL, SNESObjectiveComputeFunctionDefaultFD, NULL));
1131:   flg = PETSC_FALSE;
1132:   PetscCall(PetscOptionsBool("-snes_fd_color", "Use finite differences with coloring to compute Jacobian", "SNESComputeJacobianDefaultColor", flg, &flg, NULL));
1133:   if (flg) {
1134:     DM dm;
1135:     PetscCall(SNESGetDM(snes, &dm));
1136:     PetscCall(DMSNESUnsetJacobianContext_Internal(dm));
1137:     PetscCall(SNESSetJacobian(snes, snes->jacobian, snes->jacobian_pre, SNESComputeJacobianDefaultColor, NULL));
1138:     PetscCall(PetscInfo(snes, "Setting default finite difference coloring Jacobian matrix\n"));
1139:   }
1141:   flg = PETSC_FALSE;
1142:   PetscCall(PetscOptionsBool("-snes_mf_operator", "Use a Matrix-Free Jacobian with user-provided preconditioner matrix", "SNESSetUseMatrixFree", PETSC_FALSE, &snes->mf_operator, &flg));
1143:   if (flg && snes->mf_operator) {
1144:     snes->mf_operator = PETSC_TRUE;
1145:     snes->mf          = PETSC_TRUE;
1146:   }
1147:   flg = PETSC_FALSE;
1148:   PetscCall(PetscOptionsBool("-snes_mf", "Use a Matrix-Free Jacobian with no preconditioner matrix", "SNESSetUseMatrixFree", PETSC_FALSE, &snes->mf, &flg));
1149:   if (!flg && snes->mf_operator) snes->mf = PETSC_TRUE;
1150:   PetscCall(PetscOptionsInt("-snes_mf_version", "Matrix-Free routines version 1 or 2", "None", snes->mf_version, &snes->mf_version, NULL));
1152:   flg = PETSC_FALSE;
1153:   PetscCall(SNESGetNPCSide(snes, &pcside));
1154:   PetscCall(PetscOptionsEnum("-snes_npc_side", "SNES nonlinear preconditioner side", "SNESSetNPCSide", PCSides, (PetscEnum)pcside, (PetscEnum *)&pcside, &flg));
1155:   if (flg) PetscCall(SNESSetNPCSide(snes, pcside));
1157: #if defined(PETSC_HAVE_SAWS)
1158:   /*
1159:     Publish convergence information using SAWs
1160:   */
1161:   flg = PETSC_FALSE;
1162:   PetscCall(PetscOptionsBool("-snes_monitor_saws", "Publish SNES progress using SAWs", "SNESMonitorSet", flg, &flg, NULL));
1163:   if (flg) {
1164:     void *ctx;
1165:     PetscCall(SNESMonitorSAWsCreate(snes, &ctx));
1166:     PetscCall(SNESMonitorSet(snes, SNESMonitorSAWs, ctx, SNESMonitorSAWsDestroy));
1167:   }
1168: #endif
1169: #if defined(PETSC_HAVE_SAWS)
1170:   {
1171:     PetscBool set;
1172:     flg = PETSC_FALSE;
1173:     PetscCall(PetscOptionsBool("-snes_saws_block", "Block for SAWs at end of SNESSolve", "PetscObjectSAWsBlock", ((PetscObject)snes)->amspublishblock, &flg, &set));
1174:     if (set) PetscCall(PetscObjectSAWsSetBlock((PetscObject)snes, flg));
1175:   }
1176: #endif
1178:   for (i = 0; i < numberofsetfromoptions; i++) PetscCall((*othersetfromoptions[i])(snes));
1180:   PetscTryTypeMethod(snes, setfromoptions, PetscOptionsObject);
1182:   /* process any options handlers added with PetscObjectAddOptionsHandler() */
1183:   PetscCall(PetscObjectProcessOptionsHandlers((PetscObject)snes, PetscOptionsObject));
1184:   PetscOptionsEnd();
1186:   if (snes->linesearch) {
1187:     PetscCall(SNESGetLineSearch(snes, &snes->linesearch));
1188:     PetscCall(SNESLineSearchSetFromOptions(snes->linesearch));
1189:   }
1191:   if (snes->usesksp) {
1192:     if (!snes->ksp) PetscCall(SNESGetKSP(snes, &snes->ksp));
1193:     PetscCall(KSPSetOperators(snes->ksp, snes->jacobian, snes->jacobian_pre));
1194:     PetscCall(KSPSetFromOptions(snes->ksp));
1195:   }
1197:   /* if user has set the SNES NPC type via options database, create it. */
1198:   PetscCall(SNESGetOptionsPrefix(snes, &optionsprefix));
1199:   PetscCall(PetscOptionsHasName(((PetscObject)snes)->options, optionsprefix, "-npc_snes_type", &pcset));
1200:   if (pcset && (!snes->npc)) PetscCall(SNESGetNPC(snes, &snes->npc));
1201:   if (snes->npc) PetscCall(SNESSetFromOptions(snes->npc));
1202:   snes->setfromoptionscalled++;
1203:   PetscFunctionReturn(PETSC_SUCCESS);
1204: }
1206: /*@
1207:   SNESResetFromOptions - Sets various `SNES` and `KSP` parameters from user options ONLY if the `SNESSetFromOptions()` was previously called
1209:   Collective
1211:   Input Parameter:
1212: . snes - the `SNES` context
1214:   Level: advanced
1216: .seealso: [](ch_snes), `SNES`, `SNESSetFromOptions()`, `SNESSetOptionsPrefix()`
1217: @*/
1218: PetscErrorCode SNESResetFromOptions(SNES snes)
1219: {
1220:   PetscFunctionBegin;
1221:   if (snes->setfromoptionscalled) PetscCall(SNESSetFromOptions(snes));
1222:   PetscFunctionReturn(PETSC_SUCCESS);
1223: }
1225: /*@C
1226:   SNESSetComputeApplicationContext - Sets an optional function to compute a user-defined context for
1227:   the nonlinear solvers.
1229:   Logically Collective; No Fortran Support
1231:   Input Parameters:
1232: + snes    - the `SNES` context
1233: . compute - function to compute the context
1234: - destroy - function to destroy the context
1236:   Calling sequence of `compute`:
1237: + snes - the `SNES` context
1238: - ctx  - context to be computed
1240:   Calling sequence of `destroy`:
1241: . ctx - context to be computed by `compute()`
1243:   Level: intermediate
1245:   Note:
1246:   This routine is useful if you are performing grid sequencing or using `SNESFAS` and need the appropriate context generated for each level.
1248:   Use `SNESSetApplicationContext()` to see the context immediately
1250: .seealso: [](ch_snes), `SNESGetApplicationContext()`, `SNESSetApplicationContext()`
1251: @*/
1252: PetscErrorCode SNESSetComputeApplicationContext(SNES snes, PetscErrorCode (*compute)(SNES snes, void **ctx), PetscErrorCode (*destroy)(void **ctx))
1253: {
1254:   PetscFunctionBegin;
1256:   snes->ops->usercompute = compute;
1257:   snes->ops->userdestroy = destroy;
1258:   PetscFunctionReturn(PETSC_SUCCESS);
1259: }
1261: /*@
1262:   SNESSetApplicationContext - Sets the optional user-defined context for the nonlinear solvers.
1264:   Logically Collective
1266:   Input Parameters:
1267: + snes - the `SNES` context
1268: - usrP - optional user context
1270:   Level: intermediate
1272:   Notes:
1273:   Users can provide a context when constructing the `SNES` options and then access it inside their function, Jacobian, or other evaluation function
1274:   with `SNESGetApplicationContext()`
1276:   To provide a function that computes the context for you use `SNESSetComputeApplicationContext()`
1278:   Fortran Note:
1279:   You must write a Fortran interface definition for this
1280:   function that tells Fortran the Fortran derived data type that you are passing in as the `usrP` argument.
1282: .seealso: [](ch_snes), `SNES`, `SNESSetComputeApplicationContext()`, `SNESGetApplicationContext()`
1283: @*/
1284: PetscErrorCode SNESSetApplicationContext(SNES snes, void *usrP)
1285: {
1286:   KSP ksp;
1288:   PetscFunctionBegin;
1290:   PetscCall(SNESGetKSP(snes, &ksp));
1291:   PetscCall(KSPSetApplicationContext(ksp, usrP));
1292:   snes->user = usrP;
1293:   PetscFunctionReturn(PETSC_SUCCESS);
1294: }
1296: /*@
1297:   SNESGetApplicationContext - Gets the user-defined context for the
1298:   nonlinear solvers set with `SNESGetApplicationContext()` or `SNESSetComputeApplicationContext()`
1300:   Not Collective
1302:   Input Parameter:
1303: . snes - `SNES` context
1305:   Output Parameter:
1306: . usrP - user context
1308:   Level: intermediate
1310:   Fortran Note:
1311:   You must write a Fortran interface definition for this
1312:   function that tells Fortran the Fortran derived data type that you are passing in as the `usrP` argument.
1314: .seealso: [](ch_snes), `SNESSetApplicationContext()`, `SNESSetComputeApplicationContext()`
1315: @*/
1316: PetscErrorCode SNESGetApplicationContext(SNES snes, void *usrP)
1317: {
1318:   PetscFunctionBegin;
1320:   *(void **)usrP = snes->user;
1321:   PetscFunctionReturn(PETSC_SUCCESS);
1322: }
1324: /*@
1325:   SNESSetUseMatrixFree - indicates that `SNES` should use matrix-free finite difference matrix-vector products to apply the Jacobian.
1327:   Logically Collective
1329:   Input Parameters:
1330: + snes        - `SNES` context
1331: . mf_operator - use matrix-free only for the Amat used by `SNESSetJacobian()`, this means the user provided Pmat will continue to be used
1332: - mf          - use matrix-free for both the Amat and Pmat used by `SNESSetJacobian()`, both the Amat and Pmat set in `SNESSetJacobian()` will be ignored. With
1333:                 this option no matrix-element based preconditioners can be used in the linear solve since the matrix won't be explicitly available
1335:   Options Database Keys:
1336: + -snes_mf_operator - use matrix-free only for the mat operator
1337: . -snes_mf          - use matrix-free for both the mat and pmat operator
1338: . -snes_fd_color    - compute the Jacobian via coloring and finite differences.
1339: - -snes_fd          - compute the Jacobian via finite differences (slow)
1341:   Level: intermediate
1343:   Note:
1344:   `SNES` supports three approaches for computing (approximate) Jacobians: user provided via `SNESSetJacobian()`, matrix-free using `MatCreateSNESMF()`,
1345:   and computing explicitly with
1346:   finite differences and coloring using `MatFDColoring`. It is also possible to use automatic differentiation and the `MatFDColoring` object.
1348: .seealso: [](ch_snes), `SNES`, `SNESGetUseMatrixFree()`, `MatCreateSNESMF()`, `SNESComputeJacobianDefaultColor()`, `MatFDColoring`
1349: @*/
1350: PetscErrorCode SNESSetUseMatrixFree(SNES snes, PetscBool mf_operator, PetscBool mf)
1351: {
1352:   PetscFunctionBegin;
1356:   snes->mf          = mf_operator ? PETSC_TRUE : mf;
1357:   snes->mf_operator = mf_operator;
1358:   PetscFunctionReturn(PETSC_SUCCESS);
1359: }
1361: /*@
1362:   SNESGetUseMatrixFree - indicates if the `SNES` uses matrix-free finite difference matrix vector products to apply the Jacobian.
1364:   Not Collective, but the resulting flags will be the same on all MPI processes
1366:   Input Parameter:
1367: . snes - `SNES` context
1369:   Output Parameters:
1370: + mf_operator - use matrix-free only for the Amat used by `SNESSetJacobian()`, this means the user provided Pmat will continue to be used
1371: - mf          - use matrix-free for both the Amat and Pmat used by `SNESSetJacobian()`, both the Amat and Pmat set in `SNESSetJacobian()` will be ignored
1373:   Level: intermediate
1375: .seealso: [](ch_snes), `SNES`, `SNESSetUseMatrixFree()`, `MatCreateSNESMF()`
1376: @*/
1377: PetscErrorCode SNESGetUseMatrixFree(SNES snes, PetscBool *mf_operator, PetscBool *mf)
1378: {
1379:   PetscFunctionBegin;
1381:   if (mf) *mf = snes->mf;
1382:   if (mf_operator) *mf_operator = snes->mf_operator;
1383:   PetscFunctionReturn(PETSC_SUCCESS);
1384: }
1386: /*@
1387:   SNESGetIterationNumber - Gets the number of nonlinear iterations completed in the current or most recent `SNESSolve()`
1389:   Not Collective
1391:   Input Parameter:
1392: . snes - `SNES` context
1394:   Output Parameter:
1395: . iter - iteration number
1397:   Level: intermediate
1399:   Notes:
1400:   For example, during the computation of iteration 2 this would return 1.
1402:   This is useful for using lagged Jacobians (where one does not recompute the
1403:   Jacobian at each `SNES` iteration). For example, the code
1404: .vb
1405:       ierr = SNESGetIterationNumber(snes,&it);
1406:       if (!(it % 2)) {
1407:         [compute Jacobian here]
1408:       }
1409: .ve
1410:   can be used in your function that computes the Jacobian to cause the Jacobian to be
1411:   recomputed every second `SNES` iteration. See also `SNESSetLagJacobian()`
1413:   After the `SNES` solve is complete this will return the number of nonlinear iterations used.
1415: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESSetLagJacobian()`, `SNESGetLinearSolveIterations()`, `SNESSetMonitor()`
1416: @*/
1417: PetscErrorCode SNESGetIterationNumber(SNES snes, PetscInt *iter)
1418: {
1419:   PetscFunctionBegin;
1421:   PetscAssertPointer(iter, 2);
1422:   *iter = snes->iter;
1423:   PetscFunctionReturn(PETSC_SUCCESS);
1424: }
1426: /*@
1427:   SNESSetIterationNumber - Sets the current iteration number.
1429:   Not Collective
1431:   Input Parameters:
1432: + snes - `SNES` context
1433: - iter - iteration number
1435:   Level: developer
1437:   Note:
1438:   This should only be called inside a `SNES` nonlinear solver.
1440: .seealso: [](ch_snes), `SNESGetLinearSolveIterations()`
1441: @*/
1442: PetscErrorCode SNESSetIterationNumber(SNES snes, PetscInt iter)
1443: {
1444:   PetscFunctionBegin;
1446:   PetscCall(PetscObjectSAWsTakeAccess((PetscObject)snes));
1447:   snes->iter = iter;
1448:   PetscCall(PetscObjectSAWsGrantAccess((PetscObject)snes));
1449:   PetscFunctionReturn(PETSC_SUCCESS);
1450: }
1452: /*@
1453:   SNESGetNonlinearStepFailures - Gets the number of unsuccessful steps
1454:   attempted by the nonlinear solver in the current or most recent `SNESSolve()` .
1456:   Not Collective
1458:   Input Parameter:
1459: . snes - `SNES` context
1461:   Output Parameter:
1462: . nfails - number of unsuccessful steps attempted
1464:   Level: intermediate
1466:   Note:
1467:   This counter is reset to zero for each successive call to `SNESSolve()`.
1469: .seealso: [](ch_snes), `SNES`, `SNESGetMaxLinearSolveFailures()`, `SNESGetLinearSolveIterations()`, `SNESSetMaxLinearSolveFailures()`, `SNESGetLinearSolveFailures()`,
1470:           `SNESSetMaxNonlinearStepFailures()`, `SNESGetMaxNonlinearStepFailures()`
1471: @*/
1472: PetscErrorCode SNESGetNonlinearStepFailures(SNES snes, PetscInt *nfails)
1473: {
1474:   PetscFunctionBegin;
1476:   PetscAssertPointer(nfails, 2);
1477:   *nfails = snes->numFailures;
1478:   PetscFunctionReturn(PETSC_SUCCESS);
1479: }
1481: /*@
1482:   SNESSetMaxNonlinearStepFailures - Sets the maximum number of unsuccessful steps
1483:   attempted by the nonlinear solver before it gives up and returns unconverged or generates an error
1485:   Not Collective
1487:   Input Parameters:
1488: + snes     - `SNES` context
1489: - maxFails - maximum of unsuccessful steps allowed, use `PETSC_UNLIMITED` to have no limit on the number of failures
1491:   Options Database Key:
1492: . -snes_max_fail <n> - maximum number of unsuccessful steps allowed
1494:   Level: intermediate
1496:   Developer Note:
1497:   The options database key is wrong for this function name
1499: .seealso: [](ch_snes), `SNESSetErrorIfNotConverged()`, `SNESGetMaxLinearSolveFailures()`, `SNESGetLinearSolveIterations()`, `SNESSetMaxLinearSolveFailures()`, `SNESGetLinearSolveFailures()`,
1500:           `SNESGetMaxNonlinearStepFailures()`, `SNESGetNonlinearStepFailures()`
1501: @*/
1502: PetscErrorCode SNESSetMaxNonlinearStepFailures(SNES snes, PetscInt maxFails)
1503: {
1504:   PetscFunctionBegin;
1507:   if (maxFails == PETSC_UNLIMITED) {
1508:     snes->maxFailures = PETSC_INT_MAX;
1509:   } else {
1510:     PetscCheck(maxFails >= 0, PetscObjectComm((PetscObject)snes), PETSC_ERR_ARG_OUTOFRANGE, "Cannot have a negative maximum number of failures");
1511:     snes->maxFailures = maxFails;
1512:   }
1513:   PetscFunctionReturn(PETSC_SUCCESS);
1514: }
1516: /*@
1517:   SNESGetMaxNonlinearStepFailures - Gets the maximum number of unsuccessful steps
1518:   attempted by the nonlinear solver before it gives up and returns unconverged or generates an error
1520:   Not Collective
1522:   Input Parameter:
1523: . snes - `SNES` context
1525:   Output Parameter:
1526: . maxFails - maximum of unsuccessful steps
1528:   Level: intermediate
1530: .seealso: [](ch_snes), `SNESSetErrorIfNotConverged()`, `SNESGetMaxLinearSolveFailures()`, `SNESGetLinearSolveIterations()`, `SNESSetMaxLinearSolveFailures()`, `SNESGetLinearSolveFailures()`,
1531:           `SNESSetMaxNonlinearStepFailures()`, `SNESGetNonlinearStepFailures()`
1532: @*/
1533: PetscErrorCode SNESGetMaxNonlinearStepFailures(SNES snes, PetscInt *maxFails)
1534: {
1535:   PetscFunctionBegin;
1537:   PetscAssertPointer(maxFails, 2);
1538:   *maxFails = snes->maxFailures;
1539:   PetscFunctionReturn(PETSC_SUCCESS);
1540: }
1542: /*@
1543:   SNESGetNumberFunctionEvals - Gets the number of user provided function evaluations
1544:   done by the `SNES` object in the current or most recent `SNESSolve()`
1546:   Not Collective
1548:   Input Parameter:
1549: . snes - `SNES` context
1551:   Output Parameter:
1552: . nfuncs - number of evaluations
1554:   Level: intermediate
1556:   Note:
1557:   Reset every time `SNESSolve()` is called unless `SNESSetCountersReset()` is used.
1559: .seealso: [](ch_snes), `SNES`, `SNESGetMaxLinearSolveFailures()`, `SNESGetLinearSolveIterations()`, `SNESSetMaxLinearSolveFailures()`, `SNESGetLinearSolveFailures()`, `SNESSetCountersReset()`
1560: @*/
1561: PetscErrorCode SNESGetNumberFunctionEvals(SNES snes, PetscInt *nfuncs)
1562: {
1563:   PetscFunctionBegin;
1565:   PetscAssertPointer(nfuncs, 2);
1566:   *nfuncs = snes->nfuncs;
1567:   PetscFunctionReturn(PETSC_SUCCESS);
1568: }
1570: /*@
1571:   SNESGetLinearSolveFailures - Gets the number of failed (non-converged)
1572:   linear solvers in the current or most recent `SNESSolve()`
1574:   Not Collective
1576:   Input Parameter:
1577: . snes - `SNES` context
1579:   Output Parameter:
1580: . nfails - number of failed solves
1582:   Options Database Key:
1583: . -snes_max_linear_solve_fail <num> - The number of failures before the solve is terminated
1585:   Level: intermediate
1587:   Note:
1588:   This counter is reset to zero for each successive call to `SNESSolve()`.
1590: .seealso: [](ch_snes), `SNESGetMaxLinearSolveFailures()`, `SNESGetLinearSolveIterations()`, `SNESSetMaxLinearSolveFailures()`
1591: @*/
1592: PetscErrorCode SNESGetLinearSolveFailures(SNES snes, PetscInt *nfails)
1593: {
1594:   PetscFunctionBegin;
1596:   PetscAssertPointer(nfails, 2);
1597:   *nfails = snes->numLinearSolveFailures;
1598:   PetscFunctionReturn(PETSC_SUCCESS);
1599: }
1601: /*@
1602:   SNESSetMaxLinearSolveFailures - the number of failed linear solve attempts
1603:   allowed before `SNES` returns with a diverged reason of `SNES_DIVERGED_LINEAR_SOLVE`
1605:   Logically Collective
1607:   Input Parameters:
1608: + snes     - `SNES` context
1609: - maxFails - maximum allowed linear solve failures, use `PETSC_UNLIMITED` to have no limit on the number of failures
1611:   Options Database Key:
1612: . -snes_max_linear_solve_fail <num> - The number of failures before the solve is terminated
1614:   Level: intermediate
1616:   Note:
1617:   By default this is 0; that is `SNES` returns on the first failed linear solve
1619:   Developer Note:
1620:   The options database key is wrong for this function name
1622: .seealso: [](ch_snes), `SNESSetErrorIfNotConverged()`, `SNESGetLinearSolveFailures()`, `SNESGetMaxLinearSolveFailures()`, `SNESGetLinearSolveIterations()`
1623: @*/
1624: PetscErrorCode SNESSetMaxLinearSolveFailures(SNES snes, PetscInt maxFails)
1625: {
1626:   PetscFunctionBegin;
1630:   if (maxFails == PETSC_UNLIMITED) {
1631:     snes->maxLinearSolveFailures = PETSC_INT_MAX;
1632:   } else {
1633:     PetscCheck(maxFails >= 0, PetscObjectComm((PetscObject)snes), PETSC_ERR_ARG_OUTOFRANGE, "Cannot have a negative maximum number of failures");
1634:     snes->maxLinearSolveFailures = maxFails;
1635:   }
1636:   PetscFunctionReturn(PETSC_SUCCESS);
1637: }
1639: /*@
1640:   SNESGetMaxLinearSolveFailures - gets the maximum number of linear solve failures that
1641:   are allowed before `SNES` returns as unsuccessful
1643:   Not Collective
1645:   Input Parameter:
1646: . snes - `SNES` context
1648:   Output Parameter:
1649: . maxFails - maximum of unsuccessful solves allowed
1651:   Level: intermediate
1653:   Note:
1654:   By default this is 1; that is `SNES` returns on the first failed linear solve
1656: .seealso: [](ch_snes), `SNESSetErrorIfNotConverged()`, `SNESGetLinearSolveFailures()`, `SNESGetLinearSolveIterations()`, `SNESSetMaxLinearSolveFailures()`,
1657: @*/
1658: PetscErrorCode SNESGetMaxLinearSolveFailures(SNES snes, PetscInt *maxFails)
1659: {
1660:   PetscFunctionBegin;
1662:   PetscAssertPointer(maxFails, 2);
1663:   *maxFails = snes->maxLinearSolveFailures;
1664:   PetscFunctionReturn(PETSC_SUCCESS);
1665: }
1667: /*@
1668:   SNESGetLinearSolveIterations - Gets the total number of linear iterations
1669:   used by the nonlinear solver in the most recent `SNESSolve()`
1671:   Not Collective
1673:   Input Parameter:
1674: . snes - `SNES` context
1676:   Output Parameter:
1677: . lits - number of linear iterations
1679:   Level: intermediate
1681:   Notes:
1682:   This counter is reset to zero for each successive call to `SNESSolve()` unless `SNESSetCountersReset()` is used.
1684:   If the linear solver fails inside the `SNESSolve()` the iterations for that call to the linear solver are not included. If you wish to count them
1685:   then call `KSPGetIterationNumber()` after the failed solve.
1687: .seealso: [](ch_snes), `SNES`, `SNESGetIterationNumber()`, `SNESGetLinearSolveFailures()`, `SNESGetMaxLinearSolveFailures()`, `SNESSetCountersReset()`
1688: @*/
1689: PetscErrorCode SNESGetLinearSolveIterations(SNES snes, PetscInt *lits)
1690: {
1691:   PetscFunctionBegin;
1693:   PetscAssertPointer(lits, 2);
1694:   *lits = snes->linear_its;
1695:   PetscFunctionReturn(PETSC_SUCCESS);
1696: }
1698: /*@
1699:   SNESSetCountersReset - Sets whether or not the counters for linear iterations and function evaluations
1700:   are reset every time `SNESSolve()` is called.
1702:   Logically Collective
1704:   Input Parameters:
1705: + snes  - `SNES` context
1706: - reset - whether to reset the counters or not, defaults to `PETSC_TRUE`
1708:   Level: developer
1710: .seealso: [](ch_snes), `SNESGetNumberFunctionEvals()`, `SNESGetLinearSolveIterations()`, `SNESGetNPC()`
1711: @*/
1712: PetscErrorCode SNESSetCountersReset(SNES snes, PetscBool reset)
1713: {
1714:   PetscFunctionBegin;
1717:   snes->counters_reset = reset;
1718:   PetscFunctionReturn(PETSC_SUCCESS);
1719: }
1721: /*@
1722:   SNESResetCounters - Reset counters for linear iterations and function evaluations.
1724:   Logically Collective
1726:   Input Parameters:
1727: . snes - `SNES` context
1729:   Level: developer
1731:   Note:
1732:   It honors the flag set with `SNESSetCountersReset()`
1734: .seealso: [](ch_snes), `SNESGetNumberFunctionEvals()`, `SNESGetLinearSolveIterations()`, `SNESGetNPC()`
1735: @*/
1736: PetscErrorCode SNESResetCounters(SNES snes)
1737: {
1738:   PetscFunctionBegin;
1740:   if (snes->counters_reset) {
1741:     snes->nfuncs      = 0;
1742:     snes->linear_its  = 0;
1743:     snes->numFailures = 0;
1744:   }
1745:   PetscFunctionReturn(PETSC_SUCCESS);
1746: }
1748: /*@
1749:   SNESSetKSP - Sets a `KSP` context for the `SNES` object to use
1751:   Not Collective, but the `SNES` and `KSP` objects must live on the same `MPI_Comm`
1753:   Input Parameters:
1754: + snes - the `SNES` context
1755: - ksp  - the `KSP` context
1757:   Level: developer
1759:   Notes:
1760:   The `SNES` object already has its `KSP` object, you can obtain with `SNESGetKSP()`
1761:   so this routine is rarely needed.
1763:   The `KSP` object that is already in the `SNES` object has its reference count
1764:   decreased by one when this is called.
1766: .seealso: [](ch_snes), `SNES`, `KSP`, `KSPGetPC()`, `SNESCreate()`, `KSPCreate()`
1767: @*/
1768: PetscErrorCode SNESSetKSP(SNES snes, KSP ksp)
1769: {
1770:   PetscFunctionBegin;
1773:   PetscCheckSameComm(snes, 1, ksp, 2);
1774:   PetscCall(PetscObjectReference((PetscObject)ksp));
1775:   if (snes->ksp) PetscCall(PetscObjectDereference((PetscObject)snes->ksp));
1776:   snes->ksp = ksp;
1777:   PetscFunctionReturn(PETSC_SUCCESS);
1778: }
1780: /*@
1781:   SNESParametersInitialize - Sets all the parameters in `snes` to their default value (when `SNESCreate()` was called) if they
1782:   currently contain default values
1784:   Collective
1786:   Input Parameter:
1787: . snes - the `SNES` object
1789:   Level: developer
1791:   Developer Note:
1792:   This is called by all the `SNESCreate_XXX()` routines.
1794: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESDestroy()`, `SNESSetLagPreconditioner()`, `SNESSetLagJacobian()`,
1795:           `PetscObjectParameterSetDefault()`
1796: @*/
1797: PetscErrorCode SNESParametersInitialize(SNES snes)
1798: {
1799:   PetscObjectParameterSetDefault(snes, max_its, 50);
1800:   PetscObjectParameterSetDefault(snes, max_funcs, 10000);
1801:   PetscObjectParameterSetDefault(snes, rtol, PetscDefined(USE_REAL_SINGLE) ? 1.e-5 : 1.e-8);
1802:   PetscObjectParameterSetDefault(snes, abstol, PetscDefined(USE_REAL_SINGLE) ? 1.e-25 : 1.e-50);
1803:   PetscObjectParameterSetDefault(snes, stol, PetscDefined(USE_REAL_SINGLE) ? 1.e-5 : 1.e-8);
1804:   PetscObjectParameterSetDefault(snes, divtol, 1.e4);
1805:   return PETSC_SUCCESS;
1806: }
1808: /*@
1809:   SNESCreate - Creates a nonlinear solver context used to manage a set of nonlinear solves
1811:   Collective
1813:   Input Parameter:
1814: . comm - MPI communicator
1816:   Output Parameter:
1817: . outsnes - the new `SNES` context
1819:   Options Database Keys:
1820: + -snes_mf          - Activates default matrix-free Jacobian-vector products, and no preconditioning matrix
1821: . -snes_mf_operator - Activates default matrix-free Jacobian-vector products, and a user-provided preconditioning matrix
1822:                       as set by `SNESSetJacobian()`
1823: . -snes_fd_coloring - uses a relative fast computation of the Jacobian using finite differences and a graph coloring
1824: - -snes_fd          - Uses (slow!) finite differences to compute Jacobian
1826:   Level: beginner
1828:   Developer Notes:
1829:   `SNES` always creates a `KSP` object even though many `SNES` methods do not use it. This is
1830:   unfortunate and should be fixed at some point. The flag snes->usesksp indicates if the
1831:   particular method does use `KSP` and regulates if the information about the `KSP` is printed
1832:   in `SNESView()`.
1834:   `TSSetFromOptions()` does call `SNESSetFromOptions()` which can lead to users being confused
1835:   by help messages about meaningless `SNES` options.
1837:   `SNES` always creates the snes->kspconvctx even though it is used by only one type. This should be fixed.
1839: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESDestroy()`, `SNESSetLagPreconditioner()`, `SNESSetLagJacobian()`
1840: @*/
1841: PetscErrorCode SNESCreate(MPI_Comm comm, SNES *outsnes)
1842: {
1843:   SNES       snes;
1844:   SNESKSPEW *kctx;
1846:   PetscFunctionBegin;
1847:   PetscAssertPointer(outsnes, 2);
1848:   PetscCall(SNESInitializePackage());
1850:   PetscCall(PetscHeaderCreate(snes, SNES_CLASSID, "SNES", "Nonlinear solver", "SNES", comm, SNESDestroy, SNESView));
1851:   snes->ops->converged = SNESConvergedDefault;
1852:   snes->usesksp        = PETSC_TRUE;
1853:   snes->norm           = 0.0;
1854:   snes->xnorm          = 0.0;
1855:   snes->ynorm          = 0.0;
1856:   snes->normschedule   = SNES_NORM_ALWAYS;
1857:   snes->functype       = SNES_FUNCTION_DEFAULT;
1858:   snes->ttol           = 0.0;
1860:   snes->rnorm0               = 0;
1861:   snes->nfuncs               = 0;
1862:   snes->numFailures          = 0;
1863:   snes->maxFailures          = 1;
1864:   snes->linear_its           = 0;
1865:   snes->lagjacobian          = 1;
1866:   snes->jac_iter             = 0;
1867:   snes->lagjac_persist       = PETSC_FALSE;
1868:   snes->lagpreconditioner    = 1;
1869:   snes->pre_iter             = 0;
1870:   snes->lagpre_persist       = PETSC_FALSE;
1871:   snes->numbermonitors       = 0;
1872:   snes->numberreasonviews    = 0;
1873:   snes->data                 = NULL;
1874:   snes->setupcalled          = PETSC_FALSE;
1875:   snes->ksp_ewconv           = PETSC_FALSE;
1876:   snes->nwork                = 0;
1877:   snes->work                 = NULL;
1878:   snes->nvwork               = 0;
1879:   snes->vwork                = NULL;
1880:   snes->conv_hist_len        = 0;
1881:   snes->conv_hist_max        = 0;
1882:   snes->conv_hist            = NULL;
1883:   snes->conv_hist_its        = NULL;
1884:   snes->conv_hist_reset      = PETSC_TRUE;
1885:   snes->counters_reset       = PETSC_TRUE;
1886:   snes->vec_func_init_set    = PETSC_FALSE;
1887:   snes->reason               = SNES_CONVERGED_ITERATING;
1888:   snes->npcside              = PC_RIGHT;
1889:   snes->setfromoptionscalled = 0;
1891:   snes->mf          = PETSC_FALSE;
1892:   snes->mf_operator = PETSC_FALSE;
1893:   snes->mf_version  = 1;
1895:   snes->numLinearSolveFailures = 0;
1896:   snes->maxLinearSolveFailures = 1;
1898:   snes->vizerotolerance     = 1.e-8;
1899:   snes->checkjacdomainerror = PetscDefined(USE_DEBUG) ? PETSC_TRUE : PETSC_FALSE;
1901:   /* Set this to true if the implementation of SNESSolve_XXX does compute the residual at the final solution. */
1902:   snes->alwayscomputesfinalresidual = PETSC_FALSE;
1904:   /* Create context to compute Eisenstat-Walker relative tolerance for KSP */
1905:   PetscCall(PetscNew(&kctx));
1907:   snes->kspconvctx  = (void *)kctx;
1908:   kctx->version     = 2;
1909:   kctx->rtol_0      = 0.3; /* Eisenstat and Walker suggest rtol_0=.5, but
1910:                              this was too large for some test cases */
1911:   kctx->rtol_last   = 0.0;
1912:   kctx->rtol_max    = 0.9;
1913:   kctx->gamma       = 1.0;
1914:   kctx->alpha       = 0.5 * (1.0 + PetscSqrtReal(5.0));
1915:   kctx->alpha2      = kctx->alpha;
1916:   kctx->threshold   = 0.1;
1917:   kctx->lresid_last = 0.0;
1918:   kctx->norm_last   = 0.0;
1920:   kctx->rk_last     = 0.0;
1921:   kctx->rk_last_2   = 0.0;
1922:   kctx->rtol_last_2 = 0.0;
1923:   kctx->v4_p1       = 0.1;
1924:   kctx->v4_p2       = 0.4;
1925:   kctx->v4_p3       = 0.7;
1926:   kctx->v4_m1       = 0.8;
1927:   kctx->v4_m2       = 0.5;
1928:   kctx->v4_m3       = 0.1;
1929:   kctx->v4_m4       = 0.5;
1931:   PetscCall(SNESParametersInitialize(snes));
1932:   *outsnes = snes;
1933:   PetscFunctionReturn(PETSC_SUCCESS);
1934: }
1936: /*@C
1937:   SNESSetFunction - Sets the function evaluation routine and function
1938:   vector for use by the `SNES` routines in solving systems of nonlinear
1939:   equations.
1941:   Logically Collective
1943:   Input Parameters:
1944: + snes - the `SNES` context
1945: . r    - vector to store function values, may be `NULL`
1946: . f    - function evaluation routine;  for calling sequence see `SNESFunctionFn`
1947: - ctx  - [optional] user-defined context for private data for the
1948:          function evaluation routine (may be `NULL`)
1950:   Level: beginner
1952: .seealso: [](ch_snes), `SNES`, `SNESGetFunction()`, `SNESComputeFunction()`, `SNESSetJacobian()`, `SNESSetPicard()`, `SNESFunctionFn`
1953: @*/
1954: PetscErrorCode SNESSetFunction(SNES snes, Vec r, SNESFunctionFn *f, void *ctx)
1955: {
1956:   DM dm;
1958:   PetscFunctionBegin;
1960:   if (r) {
1962:     PetscCheckSameComm(snes, 1, r, 2);
1963:     PetscCall(PetscObjectReference((PetscObject)r));
1964:     PetscCall(VecDestroy(&snes->vec_func));
1965:     snes->vec_func = r;
1966:   }
1967:   PetscCall(SNESGetDM(snes, &dm));
1968:   PetscCall(DMSNESSetFunction(dm, f, ctx));
1969:   if (f == SNESPicardComputeFunction) PetscCall(DMSNESSetMFFunction(dm, SNESPicardComputeMFFunction, ctx));
1970:   PetscFunctionReturn(PETSC_SUCCESS);
1971: }
1973: /*@C
1974:   SNESSetInitialFunction - Set an already computed function evaluation at the initial guess to be reused by `SNESSolve()`.
1976:   Logically Collective
1978:   Input Parameters:
1979: + snes - the `SNES` context
1980: - f    - vector to store function value
1982:   Level: developer
1984:   Notes:
1985:   This should not be modified during the solution procedure.
1987:   This is used extensively in the `SNESFAS` hierarchy and in nonlinear preconditioning.
1989: .seealso: [](ch_snes), `SNES`, `SNESFAS`, `SNESSetFunction()`, `SNESComputeFunction()`, `SNESSetInitialFunctionNorm()`
1990: @*/
1991: PetscErrorCode SNESSetInitialFunction(SNES snes, Vec f)
1992: {
1993:   Vec vec_func;
1995:   PetscFunctionBegin;
1998:   PetscCheckSameComm(snes, 1, f, 2);
1999:   if (snes->npcside == PC_LEFT && snes->functype == SNES_FUNCTION_PRECONDITIONED) {
2000:     snes->vec_func_init_set = PETSC_FALSE;
2001:     PetscFunctionReturn(PETSC_SUCCESS);
2002:   }
2003:   PetscCall(SNESGetFunction(snes, &vec_func, NULL, NULL));
2004:   PetscCall(VecCopy(f, vec_func));
2006:   snes->vec_func_init_set = PETSC_TRUE;
2007:   PetscFunctionReturn(PETSC_SUCCESS);
2008: }
2010: /*@
2011:   SNESSetNormSchedule - Sets the `SNESNormSchedule` used in convergence and monitoring
2012:   of the `SNES` method, when norms are computed in the solving process
2014:   Logically Collective
2016:   Input Parameters:
2017: + snes         - the `SNES` context
2018: - normschedule - the frequency of norm computation
2020:   Options Database Key:
2021: . -snes_norm_schedule <none, always, initialonly, finalonly, initialfinalonly> - set the schedule
2023:   Level: advanced
2025:   Notes:
2026:   Only certain `SNES` methods support certain `SNESNormSchedules`.  Most require evaluation
2027:   of the nonlinear function and the taking of its norm at every iteration to
2028:   even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
2029:   `SNESNGS` and the like do not require the norm of the function to be computed, and therefore
2030:   may either be monitored for convergence or not.  As these are often used as nonlinear
2031:   preconditioners, monitoring the norm of their error is not a useful enterprise within
2032:   their solution.
2034: .seealso: [](ch_snes), `SNESNormSchedule`, `SNESGetNormSchedule()`, `SNESComputeFunction()`, `VecNorm()`, `SNESSetFunction()`, `SNESSetInitialFunction()`
2035: @*/
2036: PetscErrorCode SNESSetNormSchedule(SNES snes, SNESNormSchedule normschedule)
2037: {
2038:   PetscFunctionBegin;
2040:   snes->normschedule = normschedule;
2041:   PetscFunctionReturn(PETSC_SUCCESS);
2042: }
2044: /*@
2045:   SNESGetNormSchedule - Gets the `SNESNormSchedule` used in convergence and monitoring
2046:   of the `SNES` method.
2048:   Logically Collective
2050:   Input Parameters:
2051: + snes         - the `SNES` context
2052: - normschedule - the type of the norm used
2054:   Level: advanced
2056: .seealso: [](ch_snes), `SNES`, `SNESSetNormSchedule()`, `SNESComputeFunction()`, `VecNorm()`, `SNESSetFunction()`, `SNESSetInitialFunction()`, `SNESNormSchedule`
2057: @*/
2058: PetscErrorCode SNESGetNormSchedule(SNES snes, SNESNormSchedule *normschedule)
2059: {
2060:   PetscFunctionBegin;
2062:   *normschedule = snes->normschedule;
2063:   PetscFunctionReturn(PETSC_SUCCESS);
2064: }
2066: /*@
2067:   SNESSetFunctionNorm - Sets the last computed residual norm.
2069:   Logically Collective
2071:   Input Parameters:
2072: + snes - the `SNES` context
2073: - norm - the value of the norm
2075:   Level: developer
2077: .seealso: [](ch_snes), `SNES`, `SNESGetNormSchedule()`, `SNESComputeFunction()`, `VecNorm()`, `SNESSetFunction()`, `SNESSetInitialFunction()`, `SNESNormSchedule`
2078: @*/
2079: PetscErrorCode SNESSetFunctionNorm(SNES snes, PetscReal norm)
2080: {
2081:   PetscFunctionBegin;
2083:   snes->norm = norm;
2084:   PetscFunctionReturn(PETSC_SUCCESS);
2085: }
2087: /*@
2088:   SNESGetFunctionNorm - Gets the last computed norm of the residual
2090:   Not Collective
2092:   Input Parameter:
2093: . snes - the `SNES` context
2095:   Output Parameter:
2096: . norm - the last computed residual norm
2098:   Level: developer
2100: .seealso: [](ch_snes), `SNES`, `SNESSetNormSchedule()`, `SNESComputeFunction()`, `VecNorm()`, `SNESSetFunction()`, `SNESSetInitialFunction()`, `SNESNormSchedule`
2101: @*/
2102: PetscErrorCode SNESGetFunctionNorm(SNES snes, PetscReal *norm)
2103: {
2104:   PetscFunctionBegin;
2106:   PetscAssertPointer(norm, 2);
2107:   *norm = snes->norm;
2108:   PetscFunctionReturn(PETSC_SUCCESS);
2109: }
2111: /*@
2112:   SNESGetUpdateNorm - Gets the last computed norm of the solution update
2114:   Not Collective
2116:   Input Parameter:
2117: . snes - the `SNES` context
2119:   Output Parameter:
2120: . ynorm - the last computed update norm
2122:   Level: developer
2124:   Note:
2125:   The new solution is the current solution plus the update, so this norm is an indication of the size of the update
2127: .seealso: [](ch_snes), `SNES`, `SNESSetNormSchedule()`, `SNESComputeFunction()`, `SNESGetFunctionNorm()`
2128: @*/
2129: PetscErrorCode SNESGetUpdateNorm(SNES snes, PetscReal *ynorm)
2130: {
2131:   PetscFunctionBegin;
2133:   PetscAssertPointer(ynorm, 2);
2134:   *ynorm = snes->ynorm;
2135:   PetscFunctionReturn(PETSC_SUCCESS);
2136: }
2138: /*@
2139:   SNESGetSolutionNorm - Gets the last computed norm of the solution
2141:   Not Collective
2143:   Input Parameter:
2144: . snes - the `SNES` context
2146:   Output Parameter:
2147: . xnorm - the last computed solution norm
2149:   Level: developer
2151: .seealso: [](ch_snes), `SNES`, `SNESSetNormSchedule()`, `SNESComputeFunction()`, `SNESGetFunctionNorm()`, `SNESGetUpdateNorm()`
2152: @*/
2153: PetscErrorCode SNESGetSolutionNorm(SNES snes, PetscReal *xnorm)
2154: {
2155:   PetscFunctionBegin;
2157:   PetscAssertPointer(xnorm, 2);
2158:   *xnorm = snes->xnorm;
2159:   PetscFunctionReturn(PETSC_SUCCESS);
2160: }
2162: /*@
2163:   SNESSetFunctionType - Sets the `SNESFunctionType`
2164:   of the `SNES` method.
2166:   Logically Collective
2168:   Input Parameters:
2169: + snes - the `SNES` context
2170: - type - the function type
2172:   Level: developer
2174:   Values of the function type\:
2175: +  `SNES_FUNCTION_DEFAULT`          - the default for the given `SNESType`
2176: .  `SNES_FUNCTION_UNPRECONDITIONED` - an unpreconditioned function evaluation (this is the function provided with `SNESSetFunction()`
2177: -  `SNES_FUNCTION_PRECONDITIONED`   - a transformation of the function provided with `SNESSetFunction()`
2179:   Note:
2180:   Different `SNESType`s use this value in different ways
2182: .seealso: [](ch_snes), `SNES`, `SNESFunctionType`, `SNESGetNormSchedule()`, `SNESComputeFunction()`, `VecNorm()`, `SNESSetFunction()`, `SNESSetInitialFunction()`, `SNESNormSchedule`
2183: @*/
2184: PetscErrorCode SNESSetFunctionType(SNES snes, SNESFunctionType type)
2185: {
2186:   PetscFunctionBegin;
2188:   snes->functype = type;
2189:   PetscFunctionReturn(PETSC_SUCCESS);
2190: }
2192: /*@
2193:   SNESGetFunctionType - Gets the `SNESFunctionType` used in convergence and monitoring set with `SNESSetFunctionType()`
2194:   of the SNES method.
2196:   Logically Collective
2198:   Input Parameters:
2199: + snes - the `SNES` context
2200: - type - the type of the function evaluation, see `SNESSetFunctionType()`
2202:   Level: advanced
2204: .seealso: [](ch_snes), `SNESSetFunctionType()`, `SNESFunctionType`, `SNESSetNormSchedule()`, `SNESComputeFunction()`, `VecNorm()`, `SNESSetFunction()`, `SNESSetInitialFunction()`, `SNESNormSchedule`
2205: @*/
2206: PetscErrorCode SNESGetFunctionType(SNES snes, SNESFunctionType *type)
2207: {
2208:   PetscFunctionBegin;
2210:   *type = snes->functype;
2211:   PetscFunctionReturn(PETSC_SUCCESS);
2212: }
2214: /*@C
2215:   SNESSetNGS - Sets the user nonlinear Gauss-Seidel routine for
2216:   use with composed nonlinear solvers.
2218:   Input Parameters:
2219: + snes - the `SNES` context, usually of the `SNESType` `SNESNGS`
2220: . f    - function evaluation routine to apply Gauss-Seidel, see `SNESNGSFn` for calling sequence
2221: - ctx  - [optional] user-defined context for private data for the smoother evaluation routine (may be `NULL`)
2223:   Level: intermediate
2225:   Note:
2226:   The `SNESNGS` routines are used by the composed nonlinear solver to generate
2227:   a problem appropriate update to the solution, particularly `SNESFAS`.
2229: .seealso: [](ch_snes), `SNESNGS`, `SNESGetNGS()`, `SNESNCG`, `SNESGetFunction()`, `SNESComputeNGS()`, `SNESNGSFn`
2230: @*/
2231: PetscErrorCode SNESSetNGS(SNES snes, SNESNGSFn *f, void *ctx)
2232: {
2233:   DM dm;
2235:   PetscFunctionBegin;
2237:   PetscCall(SNESGetDM(snes, &dm));
2238:   PetscCall(DMSNESSetNGS(dm, f, ctx));
2239:   PetscFunctionReturn(PETSC_SUCCESS);
2240: }
2242: /*
2243:      This is used for -snes_mf_operator; it uses a duplicate of snes->jacobian_pre because snes->jacobian_pre cannot be
2244:    changed during the KSPSolve()
2245: */
2246: PetscErrorCode SNESPicardComputeMFFunction(SNES snes, Vec x, Vec f, void *ctx)
2247: {
2248:   DM     dm;
2249:   DMSNES sdm;
2251:   PetscFunctionBegin;
2252:   PetscCall(SNESGetDM(snes, &dm));
2253:   PetscCall(DMGetDMSNES(dm, &sdm));
2254:   /*  A(x)*x - b(x) */
2255:   if (sdm->ops->computepfunction) {
2256:     PetscCallBack("SNES Picard callback function", (*sdm->ops->computepfunction)(snes, x, f, sdm->pctx));
2257:     PetscCall(VecScale(f, -1.0));
2258:     /* Cannot share nonzero pattern because of the possible use of SNESComputeJacobianDefault() */
2259:     if (!snes->picard) PetscCall(MatDuplicate(snes->jacobian_pre, MAT_DO_NOT_COPY_VALUES, &snes->picard));
2260:     PetscCallBack("SNES Picard callback Jacobian", (*sdm->ops->computepjacobian)(snes, x, snes->picard, snes->picard, sdm->pctx));
2261:     PetscCall(MatMultAdd(snes->picard, x, f, f));
2262:   } else {
2263:     PetscCallBack("SNES Picard callback Jacobian", (*sdm->ops->computepjacobian)(snes, x, snes->picard, snes->picard, sdm->pctx));
2264:     PetscCall(MatMult(snes->picard, x, f));
2265:   }
2266:   PetscFunctionReturn(PETSC_SUCCESS);
2267: }
2269: PetscErrorCode SNESPicardComputeFunction(SNES snes, Vec x, Vec f, void *ctx)
2270: {
2271:   DM     dm;
2272:   DMSNES sdm;
2274:   PetscFunctionBegin;
2275:   PetscCall(SNESGetDM(snes, &dm));
2276:   PetscCall(DMGetDMSNES(dm, &sdm));
2277:   /*  A(x)*x - b(x) */
2278:   if (sdm->ops->computepfunction) {
2279:     PetscCallBack("SNES Picard callback function", (*sdm->ops->computepfunction)(snes, x, f, sdm->pctx));
2280:     PetscCall(VecScale(f, -1.0));
2281:     PetscCallBack("SNES Picard callback Jacobian", (*sdm->ops->computepjacobian)(snes, x, snes->jacobian, snes->jacobian_pre, sdm->pctx));
2282:     PetscCall(MatMultAdd(snes->jacobian_pre, x, f, f));
2283:   } else {
2284:     PetscCallBack("SNES Picard callback Jacobian", (*sdm->ops->computepjacobian)(snes, x, snes->jacobian, snes->jacobian_pre, sdm->pctx));
2285:     PetscCall(MatMult(snes->jacobian_pre, x, f));
2286:   }
2287:   PetscFunctionReturn(PETSC_SUCCESS);
2288: }
2290: PetscErrorCode SNESPicardComputeJacobian(SNES snes, Vec x1, Mat J, Mat B, void *ctx)
2291: {
2292:   PetscFunctionBegin;
2293:   /* the jacobian matrix should be pre-filled in SNESPicardComputeFunction */
2294:   /* must assembly if matrix-free to get the last SNES solution */
2295:   PetscCall(MatAssemblyBegin(J, MAT_FINAL_ASSEMBLY));
2296:   PetscCall(MatAssemblyEnd(J, MAT_FINAL_ASSEMBLY));
2297:   PetscFunctionReturn(PETSC_SUCCESS);
2298: }
2300: /*@C
2301:   SNESSetPicard - Use `SNES` to solve the system $A(x) x = bp(x) + b $ via a Picard type iteration (Picard linearization)
2303:   Logically Collective
2305:   Input Parameters:
2306: + snes - the `SNES` context
2307: . r    - vector to store function values, may be `NULL`
2308: . bp   - function evaluation routine, may be `NULL`, for the calling sequence see `SNESFunctionFn`
2309: . Amat - matrix with which A(x) x - bp(x) - b is to be computed
2310: . Pmat - matrix from which preconditioner is computed (usually the same as `Amat`)
2311: . J    - function to compute matrix values, for the calling sequence see `SNESJacobianFn`
2312: - ctx  - [optional] user-defined context for private data for the function evaluation routine (may be `NULL`)
2314:   Level: intermediate
2316:   Notes:
2317:   It is often better to provide the nonlinear function F() and some approximation to its Jacobian directly and use
2318:   an approximate Newton solver. This interface is provided to allow porting/testing a previous Picard based code in PETSc before converting it to approximate Newton.
2320:   One can call `SNESSetPicard()` or `SNESSetFunction()` (and possibly `SNESSetJacobian()`) but cannot call both
2322:   Solves the equation $A(x) x = bp(x) - b$ via the defect correction algorithm $A(x^{n}) (x^{n+1} - x^{n}) = bp(x^{n}) + b - A(x^{n})x^{n}$.
2323:   When an exact solver is used this corresponds to the "classic" Picard $A(x^{n}) x^{n+1} = bp(x^{n}) + b$ iteration.
2325:   Run with `-snes_mf_operator` to solve the system with Newton's method using A(x^{n}) to construct the preconditioner.
2327:   We implement the defect correction form of the Picard iteration because it converges much more generally when inexact linear solvers are used then
2328:   the direct Picard iteration $A(x^n) x^{n+1} = bp(x^n) + b$
2330:   There is some controversity over the definition of a Picard iteration for nonlinear systems but almost everyone agrees that it involves a linear solve and some
2331:   believe it is the iteration  $A(x^{n}) x^{n+1} = b(x^{n})$ hence we use the name Picard. If anyone has an authoritative  reference that defines the Picard iteration
2332:   different please contact us at petsc-dev@mcs.anl.gov and we'll have an entirely new argument \:-).
2334:   When used with `-snes_mf_operator` this will run matrix-free Newton's method where the matrix-vector product is of the true Jacobian of $A(x)x - bp(x) - b$ and
2335:   A(x^{n}) is used to build the preconditioner
2337:   When used with `-snes_fd` this will compute the true Jacobian (very slowly one column at a time) and thus represent Newton's method.
2339:   When used with `-snes_fd_coloring` this will compute the Jacobian via coloring and thus represent a faster implementation of Newton's method. But the
2340:   the nonzero structure of the Jacobian is, in general larger than that of the Picard matrix A so you must provide in A the needed nonzero structure for the correct
2341:   coloring. When using `DMDA` this may mean creating the matrix A with `DMCreateMatrix()` using a wider stencil than strictly needed for A or with a `DMDA_STENCIL_BOX`.
2342:   See the comment in src/snes/tutorials/ex15.c.
2344: .seealso: [](ch_snes), `SNES`, `SNESGetFunction()`, `SNESSetFunction()`, `SNESComputeFunction()`, `SNESSetJacobian()`, `SNESGetPicard()`, `SNESLineSearchPreCheckPicard()`,
2345:           `SNESFunctionFn`, `SNESJacobianFn`
2346: @*/
2347: PetscErrorCode SNESSetPicard(SNES snes, Vec r, SNESFunctionFn *bp, Mat Amat, Mat Pmat, SNESJacobianFn *J, void *ctx)
2348: {
2349:   DM dm;
2351:   PetscFunctionBegin;
2353:   PetscCall(SNESGetDM(snes, &dm));
2354:   PetscCall(DMSNESSetPicard(dm, bp, J, ctx));
2355:   PetscCall(DMSNESSetMFFunction(dm, SNESPicardComputeMFFunction, ctx));
2356:   PetscCall(SNESSetFunction(snes, r, SNESPicardComputeFunction, ctx));
2357:   PetscCall(SNESSetJacobian(snes, Amat, Pmat, SNESPicardComputeJacobian, ctx));
2358:   PetscFunctionReturn(PETSC_SUCCESS);
2359: }
2361: /*@C
2362:   SNESGetPicard - Returns the context for the Picard iteration
2364:   Not Collective, but `Vec` is parallel if `SNES` is parallel. Collective if `Vec` is requested, but has not been created yet.
2366:   Input Parameter:
2367: . snes - the `SNES` context
2369:   Output Parameters:
2370: + r    - the function (or `NULL`)
2371: . f    - the function (or `NULL`);  for calling sequence see `SNESFunctionFn`
2372: . Amat - the matrix used to defined the operation A(x) x - b(x) (or `NULL`)
2373: . Pmat - the matrix from which the preconditioner will be constructed (or `NULL`)
2374: . J    - the function for matrix evaluation (or `NULL`);  for calling sequence see `SNESJacobianFn`
2375: - ctx  - the function context (or `NULL`)
2377:   Level: advanced
2379: .seealso: [](ch_snes), `SNESSetFunction()`, `SNESSetPicard()`, `SNESGetFunction()`, `SNESGetJacobian()`, `SNESGetDM()`, `SNESFunctionFn`, `SNESJacobianFn`
2380: @*/
2381: PetscErrorCode SNESGetPicard(SNES snes, Vec *r, SNESFunctionFn **f, Mat *Amat, Mat *Pmat, SNESJacobianFn **J, void **ctx)
2382: {
2383:   DM dm;
2385:   PetscFunctionBegin;
2387:   PetscCall(SNESGetFunction(snes, r, NULL, NULL));
2388:   PetscCall(SNESGetJacobian(snes, Amat, Pmat, NULL, NULL));
2389:   PetscCall(SNESGetDM(snes, &dm));
2390:   PetscCall(DMSNESGetPicard(dm, f, J, ctx));
2391:   PetscFunctionReturn(PETSC_SUCCESS);
2392: }
2394: /*@C
2395:   SNESSetComputeInitialGuess - Sets a routine used to compute an initial guess for the nonlinear problem
2397:   Logically Collective
2399:   Input Parameters:
2400: + snes - the `SNES` context
2401: . func - function evaluation routine, see `SNESInitialGuessFn` for the calling sequence
2402: - ctx  - [optional] user-defined context for private data for the
2403:          function evaluation routine (may be `NULL`)
2405:   Level: intermediate
2407: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESSetFunction()`, `SNESGetFunction()`, `SNESComputeFunction()`, `SNESSetJacobian()`, `SNESInitialGuessFn`
2408: @*/
2409: PetscErrorCode SNESSetComputeInitialGuess(SNES snes, SNESInitialGuessFn *func, void *ctx)
2410: {
2411:   PetscFunctionBegin;
2413:   if (func) snes->ops->computeinitialguess = func;
2414:   if (ctx) snes->initialguessP = ctx;
2415:   PetscFunctionReturn(PETSC_SUCCESS);
2416: }
2418: /*@C
2419:   SNESGetRhs - Gets the vector for solving F(x) = `rhs`. If `rhs` is not set
2420:   it assumes a zero right-hand side.
2422:   Logically Collective
2424:   Input Parameter:
2425: . snes - the `SNES` context
2427:   Output Parameter:
2428: . rhs - the right-hand side vector or `NULL` if there is no right-hand side vector
2430:   Level: intermediate
2432: .seealso: [](ch_snes), `SNES`, `SNESGetSolution()`, `SNESGetFunction()`, `SNESComputeFunction()`, `SNESSetJacobian()`, `SNESSetFunction()`
2433: @*/
2434: PetscErrorCode SNESGetRhs(SNES snes, Vec *rhs)
2435: {
2436:   PetscFunctionBegin;
2438:   PetscAssertPointer(rhs, 2);
2439:   *rhs = snes->vec_rhs;
2440:   PetscFunctionReturn(PETSC_SUCCESS);
2441: }
2443: /*@
2444:   SNESComputeFunction - Calls the function that has been set with `SNESSetFunction()`.
2446:   Collective
2448:   Input Parameters:
2449: + snes - the `SNES` context
2450: - x    - input vector
2452:   Output Parameter:
2453: . y - function vector, as set by `SNESSetFunction()`
2455:   Level: developer
2457:   Notes:
2458:   `SNESComputeFunction()` is typically used within nonlinear solvers
2459:   implementations, so users would not generally call this routine themselves.
2461:   When solving for $F(x) = b$, this routine computes $y = F(x) - b$.
2463: .seealso: [](ch_snes), `SNES`, `SNESSetFunction()`, `SNESGetFunction()`, `SNESComputeMFFunction()`
2464: @*/
2465: PetscErrorCode SNESComputeFunction(SNES snes, Vec x, Vec y)
2466: {
2467:   DM     dm;
2468:   DMSNES sdm;
2470:   PetscFunctionBegin;
2474:   PetscCheckSameComm(snes, 1, x, 2);
2475:   PetscCheckSameComm(snes, 1, y, 3);
2476:   PetscCall(VecValidValues_Internal(x, 2, PETSC_TRUE));
2478:   PetscCall(SNESGetDM(snes, &dm));
2479:   PetscCall(DMGetDMSNES(dm, &sdm));
2480:   PetscCheck(sdm->ops->computefunction || snes->vec_rhs, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetFunction() or SNESSetDM() before SNESComputeFunction(), likely called from SNESSolve().");
2481:   if (sdm->ops->computefunction) {
2482:     if (sdm->ops->computefunction != SNESObjectiveComputeFunctionDefaultFD) PetscCall(PetscLogEventBegin(SNES_FunctionEval, snes, x, y, 0));
2483:     PetscCall(VecLockReadPush(x));
2484:     /* ensure domainerror is false prior to computefunction evaluation (may not have been reset) */
2485:     snes->domainerror = PETSC_FALSE;
2486:     {
2487:       void           *ctx;
2488:       SNESFunctionFn *computefunction;
2489:       PetscCall(DMSNESGetFunction(dm, &computefunction, &ctx));
2490:       PetscCallBack("SNES callback function", (*computefunction)(snes, x, y, ctx));
2491:     }
2492:     PetscCall(VecLockReadPop(x));
2493:     if (sdm->ops->computefunction != SNESObjectiveComputeFunctionDefaultFD) PetscCall(PetscLogEventEnd(SNES_FunctionEval, snes, x, y, 0));
2494:   } else /* if (snes->vec_rhs) */ {
2495:     PetscCall(MatMult(snes->jacobian, x, y));
2496:   }
2497:   if (snes->vec_rhs) PetscCall(VecAXPY(y, -1.0, snes->vec_rhs));
2498:   snes->nfuncs++;
2499:   /*
2500:      domainerror might not be set on all processes; so we tag vector locally with Inf and the next inner product or norm will
2501:      propagate the value to all processes
2502:   */
2503:   PetscCall(VecFlag(y, snes->domainerror));
2504:   PetscFunctionReturn(PETSC_SUCCESS);
2505: }
2507: /*@
2508:   SNESComputeMFFunction - Calls the function that has been set with `DMSNESSetMFFunction()`.
2510:   Collective
2512:   Input Parameters:
2513: + snes - the `SNES` context
2514: - x    - input vector
2516:   Output Parameter:
2517: . y - output vector
2519:   Level: developer
2521:   Notes:
2522:   `SNESComputeMFFunction()` is used within the matrix-vector products called by the matrix created with `MatCreateSNESMF()`
2523:   so users would not generally call this routine themselves.
2525:   Since this function is intended for use with finite differencing it does not subtract the right-hand side vector provided with `SNESSolve()`
2526:   while `SNESComputeFunction()` does. As such, this routine cannot be used with  `MatMFFDSetBase()` with a provided F function value even if it applies the
2527:   same function as `SNESComputeFunction()` if a `SNESSolve()` right-hand side vector is use because the two functions difference would include this right hand side function.
2529: .seealso: [](ch_snes), `SNES`, `SNESSetFunction()`, `SNESGetFunction()`, `SNESComputeFunction()`, `MatCreateSNESMF()`, `DMSNESSetMFFunction()`
2530: @*/
2531: PetscErrorCode SNESComputeMFFunction(SNES snes, Vec x, Vec y)
2532: {
2533:   DM     dm;
2534:   DMSNES sdm;
2536:   PetscFunctionBegin;
2540:   PetscCheckSameComm(snes, 1, x, 2);
2541:   PetscCheckSameComm(snes, 1, y, 3);
2542:   PetscCall(VecValidValues_Internal(x, 2, PETSC_TRUE));
2544:   PetscCall(SNESGetDM(snes, &dm));
2545:   PetscCall(DMGetDMSNES(dm, &sdm));
2546:   PetscCall(PetscLogEventBegin(SNES_FunctionEval, snes, x, y, 0));
2547:   PetscCall(VecLockReadPush(x));
2548:   /* ensure domainerror is false prior to computefunction evaluation (may not have been reset) */
2549:   snes->domainerror = PETSC_FALSE;
2550:   PetscCallBack("SNES callback function", (*sdm->ops->computemffunction)(snes, x, y, sdm->mffunctionctx));
2551:   PetscCall(VecLockReadPop(x));
2552:   PetscCall(PetscLogEventEnd(SNES_FunctionEval, snes, x, y, 0));
2553:   snes->nfuncs++;
2554:   /*
2555:      domainerror might not be set on all processes; so we tag vector locally with Inf and the next inner product or norm will
2556:      propagate the value to all processes
2557:   */
2558:   PetscCall(VecFlag(y, snes->domainerror));
2559:   PetscFunctionReturn(PETSC_SUCCESS);
2560: }
2562: /*@
2563:   SNESComputeNGS - Calls the Gauss-Seidel function that has been set with `SNESSetNGS()`.
2565:   Collective
2567:   Input Parameters:
2568: + snes - the `SNES` context
2569: . x    - input vector
2570: - b    - rhs vector
2572:   Output Parameter:
2573: . x - new solution vector
2575:   Level: developer
2577:   Note:
2578:   `SNESComputeNGS()` is typically used within composed nonlinear solver
2579:   implementations, so most users would not generally call this routine
2580:   themselves.
2582: .seealso: [](ch_snes), `SNESNGSFn`, `SNESSetNGS()`, `SNESComputeFunction()`, `SNESNGS`
2583: @*/
2584: PetscErrorCode SNESComputeNGS(SNES snes, Vec b, Vec x)
2585: {
2586:   DM     dm;
2587:   DMSNES sdm;
2589:   PetscFunctionBegin;
2593:   PetscCheckSameComm(snes, 1, x, 3);
2594:   if (b) PetscCheckSameComm(snes, 1, b, 2);
2595:   if (b) PetscCall(VecValidValues_Internal(b, 2, PETSC_TRUE));
2596:   PetscCall(PetscLogEventBegin(SNES_NGSEval, snes, x, b, 0));
2597:   PetscCall(SNESGetDM(snes, &dm));
2598:   PetscCall(DMGetDMSNES(dm, &sdm));
2599:   PetscCheck(sdm->ops->computegs, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetNGS() before SNESComputeNGS(), likely called from SNESSolve().");
2600:   if (b) PetscCall(VecLockReadPush(b));
2601:   PetscCallBack("SNES callback NGS", (*sdm->ops->computegs)(snes, x, b, sdm->gsctx));
2602:   if (b) PetscCall(VecLockReadPop(b));
2603:   PetscCall(PetscLogEventEnd(SNES_NGSEval, snes, x, b, 0));
2604:   PetscFunctionReturn(PETSC_SUCCESS);
2605: }
2607: static PetscErrorCode SNESComputeFunction_FD(SNES snes, Vec Xin, Vec G)
2608: {
2609:   Vec          X;
2610:   PetscScalar *g;
2611:   PetscReal    f, f2;
2612:   PetscInt     low, high, N, i;
2613:   PetscBool    flg;
2614:   PetscReal    h = .5 * PETSC_SQRT_MACHINE_EPSILON;
2616:   PetscFunctionBegin;
2617:   PetscCall(PetscOptionsGetReal(((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_fd_delta", &h, &flg));
2618:   PetscCall(VecDuplicate(Xin, &X));
2619:   PetscCall(VecCopy(Xin, X));
2620:   PetscCall(VecGetSize(X, &N));
2621:   PetscCall(VecGetOwnershipRange(X, &low, &high));
2622:   PetscCall(VecSetOption(X, VEC_IGNORE_OFF_PROC_ENTRIES, PETSC_TRUE));
2623:   PetscCall(VecGetArray(G, &g));
2624:   for (i = 0; i < N; i++) {
2625:     PetscCall(VecSetValue(X, i, -h, ADD_VALUES));
2626:     PetscCall(VecAssemblyBegin(X));
2627:     PetscCall(VecAssemblyEnd(X));
2628:     PetscCall(SNESComputeObjective(snes, X, &f));
2629:     PetscCall(VecSetValue(X, i, 2.0 * h, ADD_VALUES));
2630:     PetscCall(VecAssemblyBegin(X));
2631:     PetscCall(VecAssemblyEnd(X));
2632:     PetscCall(SNESComputeObjective(snes, X, &f2));
2633:     PetscCall(VecSetValue(X, i, -h, ADD_VALUES));
2634:     PetscCall(VecAssemblyBegin(X));
2635:     PetscCall(VecAssemblyEnd(X));
2636:     if (i >= low && i < high) g[i - low] = (f2 - f) / (2.0 * h);
2637:   }
2638:   PetscCall(VecRestoreArray(G, &g));
2639:   PetscCall(VecDestroy(&X));
2640:   PetscFunctionReturn(PETSC_SUCCESS);
2641: }
2643: PetscErrorCode SNESTestFunction(SNES snes)
2644: {
2645:   Vec               x, g1, g2, g3;
2646:   PetscBool         complete_print = PETSC_FALSE, test = PETSC_FALSE;
2647:   PetscReal         hcnorm, fdnorm, hcmax, fdmax, diffmax, diffnorm;
2648:   PetscScalar       dot;
2649:   MPI_Comm          comm;
2650:   PetscViewer       viewer, mviewer;
2651:   PetscViewerFormat format;
2652:   PetscInt          tabs;
2653:   static PetscBool  directionsprinted = PETSC_FALSE;
2654:   SNESObjectiveFn  *objective;
2656:   PetscFunctionBegin;
2657:   PetscCall(SNESGetObjective(snes, &objective, NULL));
2658:   if (!objective) PetscFunctionReturn(PETSC_SUCCESS);
2660:   PetscObjectOptionsBegin((PetscObject)snes);
2661:   PetscCall(PetscOptionsName("-snes_test_function", "Compare hand-coded and finite difference function", "None", &test));
2662:   PetscCall(PetscOptionsViewer("-snes_test_function_view", "View difference between hand-coded and finite difference function element entries", "None", &mviewer, &format, &complete_print));
2663:   PetscOptionsEnd();
2664:   if (!test) {
2665:     if (complete_print) PetscCall(PetscViewerDestroy(&mviewer));
2666:     PetscFunctionReturn(PETSC_SUCCESS);
2667:   }
2669:   PetscCall(PetscObjectGetComm((PetscObject)snes, &comm));
2670:   PetscCall(PetscViewerASCIIGetStdout(comm, &viewer));
2671:   PetscCall(PetscViewerASCIIGetTab(viewer, &tabs));
2672:   PetscCall(PetscViewerASCIISetTab(viewer, ((PetscObject)snes)->tablevel));
2673:   PetscCall(PetscViewerASCIIPrintf(viewer, "  ---------- Testing Function -------------\n"));
2674:   if (!complete_print && !directionsprinted) {
2675:     PetscCall(PetscViewerASCIIPrintf(viewer, "  Run with -snes_test_function_view and optionally -snes_test_function <threshold> to show difference\n"));
2676:     PetscCall(PetscViewerASCIIPrintf(viewer, "    of hand-coded and finite difference function entries greater than <threshold>.\n"));
2677:   }
2678:   if (!directionsprinted) {
2679:     PetscCall(PetscViewerASCIIPrintf(viewer, "  Testing hand-coded Function, if (for double precision runs) ||F - Ffd||/||F|| is\n"));
2680:     PetscCall(PetscViewerASCIIPrintf(viewer, "    O(1.e-8), the hand-coded Function is probably correct.\n"));
2681:     directionsprinted = PETSC_TRUE;
2682:   }
2683:   if (complete_print) PetscCall(PetscViewerPushFormat(mviewer, format));
2685:   PetscCall(SNESGetSolution(snes, &x));
2686:   PetscCall(VecDuplicate(x, &g1));
2687:   PetscCall(VecDuplicate(x, &g2));
2688:   PetscCall(VecDuplicate(x, &g3));
2689:   PetscCall(SNESComputeFunction(snes, x, g1));
2690:   PetscCall(SNESComputeFunction_FD(snes, x, g2));
2692:   PetscCall(VecNorm(g2, NORM_2, &fdnorm));
2693:   PetscCall(VecNorm(g1, NORM_2, &hcnorm));
2694:   PetscCall(VecNorm(g2, NORM_INFINITY, &fdmax));
2695:   PetscCall(VecNorm(g1, NORM_INFINITY, &hcmax));
2696:   PetscCall(VecDot(g1, g2, &dot));
2697:   PetscCall(VecCopy(g1, g3));
2698:   PetscCall(VecAXPY(g3, -1.0, g2));
2699:   PetscCall(VecNorm(g3, NORM_2, &diffnorm));
2700:   PetscCall(VecNorm(g3, NORM_INFINITY, &diffmax));
2701:   PetscCall(PetscViewerASCIIPrintf(viewer, "  ||Ffd|| %g, ||F|| = %g, angle cosine = (Ffd'F)/||Ffd||||F|| = %g\n", (double)fdnorm, (double)hcnorm, (double)(PetscRealPart(dot) / (fdnorm * hcnorm))));
2702:   PetscCall(PetscViewerASCIIPrintf(viewer, "  2-norm ||F - Ffd||/||F|| = %g, ||F - Ffd|| = %g\n", (double)(diffnorm / PetscMax(hcnorm, fdnorm)), (double)diffnorm));
2703:   PetscCall(PetscViewerASCIIPrintf(viewer, "  max-norm ||F - Ffd||/||F|| = %g, ||F - Ffd|| = %g\n", (double)(diffmax / PetscMax(hcmax, fdmax)), (double)diffmax));
2705:   if (complete_print) {
2706:     PetscCall(PetscViewerASCIIPrintf(viewer, "  Hand-coded function ----------\n"));
2707:     PetscCall(VecView(g1, mviewer));
2708:     PetscCall(PetscViewerASCIIPrintf(viewer, "  Finite difference function ----------\n"));
2709:     PetscCall(VecView(g2, mviewer));
2710:     PetscCall(PetscViewerASCIIPrintf(viewer, "  Hand-coded minus finite-difference function ----------\n"));
2711:     PetscCall(VecView(g3, mviewer));
2712:   }
2713:   PetscCall(VecDestroy(&g1));
2714:   PetscCall(VecDestroy(&g2));
2715:   PetscCall(VecDestroy(&g3));
2717:   if (complete_print) {
2718:     PetscCall(PetscViewerPopFormat(mviewer));
2719:     PetscCall(PetscViewerDestroy(&mviewer));
2720:   }
2721:   PetscCall(PetscViewerASCIISetTab(viewer, tabs));
2722:   PetscFunctionReturn(PETSC_SUCCESS);
2723: }
2725: PetscErrorCode SNESTestJacobian(SNES snes)
2726: {
2727:   Mat               A, B, C, D, jacobian;
2728:   Vec               x = snes->vec_sol, f;
2729:   PetscReal         nrm, gnorm;
2730:   PetscReal         threshold = 1.e-5;
2731:   MatType           mattype;
2732:   PetscInt          m, n, M, N;
2733:   void             *functx;
2734:   PetscBool         complete_print = PETSC_FALSE, threshold_print = PETSC_FALSE, test = PETSC_FALSE, flg, istranspose;
2735:   PetscViewer       viewer, mviewer;
2736:   MPI_Comm          comm;
2737:   PetscInt          tabs;
2738:   static PetscBool  directionsprinted = PETSC_FALSE;
2739:   PetscViewerFormat format;
2741:   PetscFunctionBegin;
2742:   PetscObjectOptionsBegin((PetscObject)snes);
2743:   PetscCall(PetscOptionsName("-snes_test_jacobian", "Compare hand-coded and finite difference Jacobians", "None", &test));
2744:   PetscCall(PetscOptionsReal("-snes_test_jacobian", "Threshold for element difference between hand-coded and finite difference being meaningful", "None", threshold, &threshold, NULL));
2745:   PetscCall(PetscOptionsDeprecated("-snes_test_jacobian_display", "-snes_test_jacobian_view", "3.13", NULL));
2746:   PetscCall(PetscOptionsViewer("-snes_test_jacobian_view", "View difference between hand-coded and finite difference Jacobians element entries", "None", &mviewer, &format, &complete_print));
2747:   PetscCall(PetscOptionsDeprecated("-snes_test_jacobian_display_threshold", "-snes_test_jacobian", "3.13", "-snes_test_jacobian accepts an optional threshold (since v3.10)"));
2748:   PetscCall(PetscOptionsReal("-snes_test_jacobian_display_threshold", "Display difference between hand-coded and finite difference Jacobians which exceed input threshold", "None", threshold, &threshold, &threshold_print));
2749:   PetscOptionsEnd();
2750:   if (!test) PetscFunctionReturn(PETSC_SUCCESS);
2752:   PetscCall(PetscObjectGetComm((PetscObject)snes, &comm));
2753:   PetscCall(PetscViewerASCIIGetStdout(comm, &viewer));
2754:   PetscCall(PetscViewerASCIIGetTab(viewer, &tabs));
2755:   PetscCall(PetscViewerASCIISetTab(viewer, ((PetscObject)snes)->tablevel));
2756:   PetscCall(PetscViewerASCIIPrintf(viewer, "  ---------- Testing Jacobian -------------\n"));
2757:   if (!complete_print && !directionsprinted) {
2758:     PetscCall(PetscViewerASCIIPrintf(viewer, "  Run with -snes_test_jacobian_view and optionally -snes_test_jacobian <threshold> to show difference\n"));
2759:     PetscCall(PetscViewerASCIIPrintf(viewer, "    of hand-coded and finite difference Jacobian entries greater than <threshold>.\n"));
2760:   }
2761:   if (!directionsprinted) {
2762:     PetscCall(PetscViewerASCIIPrintf(viewer, "  Testing hand-coded Jacobian, if (for double precision runs) ||J - Jfd||_F/||J||_F is\n"));
2763:     PetscCall(PetscViewerASCIIPrintf(viewer, "    O(1.e-8), the hand-coded Jacobian is probably correct.\n"));
2764:     directionsprinted = PETSC_TRUE;
2765:   }
2766:   if (complete_print) PetscCall(PetscViewerPushFormat(mviewer, format));
2768:   PetscCall(PetscObjectTypeCompare((PetscObject)snes->jacobian, MATMFFD, &flg));
2769:   if (!flg) jacobian = snes->jacobian;
2770:   else jacobian = snes->jacobian_pre;
2772:   if (!x) PetscCall(MatCreateVecs(jacobian, &x, NULL));
2773:   else PetscCall(PetscObjectReference((PetscObject)x));
2774:   PetscCall(VecDuplicate(x, &f));
2776:   /* evaluate the function at this point because SNESComputeJacobianDefault() assumes that the function has been evaluated and put into snes->vec_func */
2777:   PetscCall(SNESComputeFunction(snes, x, f));
2778:   PetscCall(VecDestroy(&f));
2779:   PetscCall(PetscObjectTypeCompare((PetscObject)snes, SNESKSPTRANSPOSEONLY, &istranspose));
2780:   while (jacobian) {
2781:     Mat JT = NULL, Jsave = NULL;
2783:     if (istranspose) {
2784:       PetscCall(MatCreateTranspose(jacobian, &JT));
2785:       Jsave    = jacobian;
2786:       jacobian = JT;
2787:     }
2788:     PetscCall(PetscObjectBaseTypeCompareAny((PetscObject)jacobian, &flg, MATSEQAIJ, MATMPIAIJ, MATSEQDENSE, MATMPIDENSE, MATSEQBAIJ, MATMPIBAIJ, MATSEQSBAIJ, MATMPISBAIJ, ""));
2789:     if (flg) {
2790:       A = jacobian;
2791:       PetscCall(PetscObjectReference((PetscObject)A));
2792:     } else {
2793:       PetscCall(MatComputeOperator(jacobian, MATAIJ, &A));
2794:     }
2796:     PetscCall(MatGetType(A, &mattype));
2797:     PetscCall(MatGetSize(A, &M, &N));
2798:     PetscCall(MatGetLocalSize(A, &m, &n));
2799:     PetscCall(MatCreate(PetscObjectComm((PetscObject)A), &B));
2800:     PetscCall(MatSetType(B, mattype));
2801:     PetscCall(MatSetSizes(B, m, n, M, N));
2802:     PetscCall(MatSetBlockSizesFromMats(B, A, A));
2803:     PetscCall(MatSetUp(B));
2804:     PetscCall(MatSetOption(B, MAT_NEW_NONZERO_ALLOCATION_ERR, PETSC_FALSE));
2806:     PetscCall(SNESGetFunction(snes, NULL, NULL, &functx));
2807:     PetscCall(SNESComputeJacobianDefault(snes, x, B, B, functx));
2809:     PetscCall(MatDuplicate(B, MAT_COPY_VALUES, &D));
2810:     PetscCall(MatAYPX(D, -1.0, A, DIFFERENT_NONZERO_PATTERN));
2811:     PetscCall(MatNorm(D, NORM_FROBENIUS, &nrm));
2812:     PetscCall(MatNorm(A, NORM_FROBENIUS, &gnorm));
2813:     PetscCall(MatDestroy(&D));
2814:     if (!gnorm) gnorm = 1; /* just in case */
2815:     PetscCall(PetscViewerASCIIPrintf(viewer, "  ||J - Jfd||_F/||J||_F = %g, ||J - Jfd||_F = %g\n", (double)(nrm / gnorm), (double)nrm));
2817:     if (complete_print) {
2818:       PetscCall(PetscViewerASCIIPrintf(viewer, "  Hand-coded Jacobian ----------\n"));
2819:       PetscCall(MatView(A, mviewer));
2820:       PetscCall(PetscViewerASCIIPrintf(viewer, "  Finite difference Jacobian ----------\n"));
2821:       PetscCall(MatView(B, mviewer));
2822:     }
2824:     if (threshold_print || complete_print) {
2825:       PetscInt           Istart, Iend, *ccols, bncols, cncols, j, row;
2826:       PetscScalar       *cvals;
2827:       const PetscInt    *bcols;
2828:       const PetscScalar *bvals;
2830:       PetscCall(MatCreate(PetscObjectComm((PetscObject)A), &C));
2831:       PetscCall(MatSetType(C, mattype));
2832:       PetscCall(MatSetSizes(C, m, n, M, N));
2833:       PetscCall(MatSetBlockSizesFromMats(C, A, A));
2834:       PetscCall(MatSetUp(C));
2835:       PetscCall(MatSetOption(C, MAT_NEW_NONZERO_ALLOCATION_ERR, PETSC_FALSE));
2837:       PetscCall(MatAYPX(B, -1.0, A, DIFFERENT_NONZERO_PATTERN));
2838:       PetscCall(MatGetOwnershipRange(B, &Istart, &Iend));
2840:       for (row = Istart; row < Iend; row++) {
2841:         PetscCall(MatGetRow(B, row, &bncols, &bcols, &bvals));
2842:         PetscCall(PetscMalloc2(bncols, &ccols, bncols, &cvals));
2843:         for (j = 0, cncols = 0; j < bncols; j++) {
2844:           if (PetscAbsScalar(bvals[j]) > threshold) {
2845:             ccols[cncols] = bcols[j];
2846:             cvals[cncols] = bvals[j];
2847:             cncols += 1;
2848:           }
2849:         }
2850:         if (cncols) PetscCall(MatSetValues(C, 1, &row, cncols, ccols, cvals, INSERT_VALUES));
2851:         PetscCall(MatRestoreRow(B, row, &bncols, &bcols, &bvals));
2852:         PetscCall(PetscFree2(ccols, cvals));
2853:       }
2854:       PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
2855:       PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
2856:       PetscCall(PetscViewerASCIIPrintf(viewer, "  Hand-coded minus finite-difference Jacobian with tolerance %g ----------\n", (double)threshold));
2857:       PetscCall(MatView(C, complete_print ? mviewer : viewer));
2858:       PetscCall(MatDestroy(&C));
2859:     }
2860:     PetscCall(MatDestroy(&A));
2861:     PetscCall(MatDestroy(&B));
2862:     PetscCall(MatDestroy(&JT));
2863:     if (Jsave) jacobian = Jsave;
2864:     if (jacobian != snes->jacobian_pre) {
2865:       jacobian = snes->jacobian_pre;
2866:       PetscCall(PetscViewerASCIIPrintf(viewer, "  ---------- Testing Jacobian for preconditioner -------------\n"));
2867:     } else jacobian = NULL;
2868:   }
2869:   PetscCall(VecDestroy(&x));
2870:   if (complete_print) PetscCall(PetscViewerPopFormat(mviewer));
2871:   if (mviewer) PetscCall(PetscViewerDestroy(&mviewer));
2872:   PetscCall(PetscViewerASCIISetTab(viewer, tabs));
2873:   PetscFunctionReturn(PETSC_SUCCESS);
2874: }
2876: /*@
2877:   SNESComputeJacobian - Computes the Jacobian matrix that has been set with `SNESSetJacobian()`.
2879:   Collective
2881:   Input Parameters:
2882: + snes - the `SNES` context
2883: - X    - input vector
2885:   Output Parameters:
2886: + A - Jacobian matrix
2887: - B - optional matrix for building the preconditioner, usually the same as `A`
2889:   Options Database Keys:
2890: + -snes_lag_preconditioner <lag>           - how often to rebuild preconditioner
2891: . -snes_lag_jacobian <lag>                 - how often to rebuild Jacobian
2892: . -snes_test_jacobian <optional threshold> - compare the user provided Jacobian with one compute via finite differences to check for errors.  If a threshold is given, display only those entries whose difference is greater than the threshold.
2893: . -snes_test_jacobian_view                 - display the user provided Jacobian, the finite difference Jacobian and the difference between them to help users detect the location of errors in the user provided Jacobian
2894: . -snes_compare_explicit                   - Compare the computed Jacobian to the finite difference Jacobian and output the differences
2895: . -snes_compare_explicit_draw              - Compare the computed Jacobian to the finite difference Jacobian and draw the result
2896: . -snes_compare_explicit_contour           - Compare the computed Jacobian to the finite difference Jacobian and draw a contour plot with the result
2897: . -snes_compare_operator                   - Make the comparison options above use the operator instead of the preconditioning matrix
2898: . -snes_compare_coloring                   - Compute the finite difference Jacobian using coloring and display norms of difference
2899: . -snes_compare_coloring_display           - Compute the finite difference Jacobian using coloring and display verbose differences
2900: . -snes_compare_coloring_threshold         - Display only those matrix entries that differ by more than a given threshold
2901: . -snes_compare_coloring_threshold_atol    - Absolute tolerance for difference in matrix entries to be displayed by `-snes_compare_coloring_threshold`
2902: . -snes_compare_coloring_threshold_rtol    - Relative tolerance for difference in matrix entries to be displayed by `-snes_compare_coloring_threshold`
2903: . -snes_compare_coloring_draw              - Compute the finite difference Jacobian using coloring and draw differences
2904: - -snes_compare_coloring_draw_contour      - Compute the finite difference Jacobian using coloring and show contours of matrices and differences
2906:   Level: developer
2908:   Note:
2909:   Most users should not need to explicitly call this routine, as it
2910:   is used internally within the nonlinear solvers.
2912:   Developer Note:
2913:   This has duplicative ways of checking the accuracy of the user provided Jacobian (see the options above). This is for historical reasons, the routine `SNESTestJacobian()` use to used
2914:   with the `SNESType` of test that has been removed.
2916: .seealso: [](ch_snes), `SNESSetJacobian()`, `KSPSetOperators()`, `MatStructure`, `SNESSetLagPreconditioner()`, `SNESSetLagJacobian()`
2917: @*/
2918: PetscErrorCode SNESComputeJacobian(SNES snes, Vec X, Mat A, Mat B)
2919: {
2920:   PetscBool flag;
2921:   DM        dm;
2922:   DMSNES    sdm;
2923:   KSP       ksp;
2925:   PetscFunctionBegin;
2928:   PetscCheckSameComm(snes, 1, X, 2);
2929:   PetscCall(VecValidValues_Internal(X, 2, PETSC_TRUE));
2930:   PetscCall(SNESGetDM(snes, &dm));
2931:   PetscCall(DMGetDMSNES(dm, &sdm));
2933:   /* make sure that MatAssemblyBegin/End() is called on A matrix if it is matrix-free */
2934:   if (snes->lagjacobian == -2) {
2935:     snes->lagjacobian = -1;
2937:     PetscCall(PetscInfo(snes, "Recomputing Jacobian/preconditioner because lag is -2 (means compute Jacobian, but then never again) \n"));
2938:   } else if (snes->lagjacobian == -1) {
2939:     PetscCall(PetscInfo(snes, "Reusing Jacobian/preconditioner because lag is -1\n"));
2940:     PetscCall(PetscObjectTypeCompare((PetscObject)A, MATMFFD, &flag));
2941:     if (flag) {
2942:       PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
2943:       PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));
2944:     }
2945:     PetscFunctionReturn(PETSC_SUCCESS);
2946:   } else if (snes->lagjacobian > 1 && (snes->iter + snes->jac_iter) % snes->lagjacobian) {
2947:     PetscCall(PetscInfo(snes, "Reusing Jacobian/preconditioner because lag is %" PetscInt_FMT " and SNES iteration is %" PetscInt_FMT "\n", snes->lagjacobian, snes->iter));
2948:     PetscCall(PetscObjectTypeCompare((PetscObject)A, MATMFFD, &flag));
2949:     if (flag) {
2950:       PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
2951:       PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));
2952:     }
2953:     PetscFunctionReturn(PETSC_SUCCESS);
2954:   }
2955:   if (snes->npc && snes->npcside == PC_LEFT) {
2956:     PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
2957:     PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));
2958:     PetscFunctionReturn(PETSC_SUCCESS);
2959:   }
2961:   PetscCall(PetscLogEventBegin(SNES_JacobianEval, snes, X, A, B));
2962:   PetscCall(VecLockReadPush(X));
2963:   {
2964:     void           *ctx;
2965:     SNESJacobianFn *J;
2966:     PetscCall(DMSNESGetJacobian(dm, &J, &ctx));
2967:     PetscCallBack("SNES callback Jacobian", (*J)(snes, X, A, B, ctx));
2968:   }
2969:   PetscCall(VecLockReadPop(X));
2970:   PetscCall(PetscLogEventEnd(SNES_JacobianEval, snes, X, A, B));
2972:   /* attach latest linearization point to the preconditioning matrix */
2973:   PetscCall(PetscObjectCompose((PetscObject)B, "__SNES_latest_X", (PetscObject)X));
2975:   /* the next line ensures that snes->ksp exists */
2976:   PetscCall(SNESGetKSP(snes, &ksp));
2977:   if (snes->lagpreconditioner == -2) {
2978:     PetscCall(PetscInfo(snes, "Rebuilding preconditioner exactly once since lag is -2\n"));
2979:     PetscCall(KSPSetReusePreconditioner(snes->ksp, PETSC_FALSE));
2980:     snes->lagpreconditioner = -1;
2981:   } else if (snes->lagpreconditioner == -1) {
2982:     PetscCall(PetscInfo(snes, "Reusing preconditioner because lag is -1\n"));
2983:     PetscCall(KSPSetReusePreconditioner(snes->ksp, PETSC_TRUE));
2984:   } else if (snes->lagpreconditioner > 1 && (snes->iter + snes->pre_iter) % snes->lagpreconditioner) {
2985:     PetscCall(PetscInfo(snes, "Reusing preconditioner because lag is %" PetscInt_FMT " and SNES iteration is %" PetscInt_FMT "\n", snes->lagpreconditioner, snes->iter));
2986:     PetscCall(KSPSetReusePreconditioner(snes->ksp, PETSC_TRUE));
2987:   } else {
2988:     PetscCall(PetscInfo(snes, "Rebuilding preconditioner\n"));
2989:     PetscCall(KSPSetReusePreconditioner(snes->ksp, PETSC_FALSE));
2990:   }
2992:   /* monkey business to allow testing Jacobians in multilevel solvers.
2993:      This is needed because the SNESTestXXX interface does not accept vectors and matrices */
2994:   {
2995:     Vec xsave            = snes->vec_sol;
2996:     Mat jacobiansave     = snes->jacobian;
2997:     Mat jacobian_presave = snes->jacobian_pre;
2999:     snes->vec_sol      = X;
3000:     snes->jacobian     = A;
3001:     snes->jacobian_pre = B;
3002:     PetscCall(SNESTestFunction(snes));
3003:     PetscCall(SNESTestJacobian(snes));
3005:     snes->vec_sol      = xsave;
3006:     snes->jacobian     = jacobiansave;
3007:     snes->jacobian_pre = jacobian_presave;
3008:   }
3010:   {
3011:     PetscBool flag = PETSC_FALSE, flag_draw = PETSC_FALSE, flag_contour = PETSC_FALSE, flag_operator = PETSC_FALSE;
3012:     PetscCall(PetscOptionsCreateViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_compare_explicit", NULL, NULL, &flag));
3013:     PetscCall(PetscOptionsCreateViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_compare_explicit_draw", NULL, NULL, &flag_draw));
3014:     PetscCall(PetscOptionsCreateViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_compare_explicit_draw_contour", NULL, NULL, &flag_contour));
3015:     PetscCall(PetscOptionsCreateViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_compare_operator", NULL, NULL, &flag_operator));
3016:     if (flag || flag_draw || flag_contour) {
3017:       Mat         Bexp_mine = NULL, Bexp, FDexp;
3018:       PetscViewer vdraw, vstdout;
3019:       PetscBool   flg;
3020:       if (flag_operator) {
3021:         PetscCall(MatComputeOperator(A, MATAIJ, &Bexp_mine));
3022:         Bexp = Bexp_mine;
3023:       } else {
3024:         /* See if the preconditioning matrix can be viewed and added directly */
3025:         PetscCall(PetscObjectBaseTypeCompareAny((PetscObject)B, &flg, MATSEQAIJ, MATMPIAIJ, MATSEQDENSE, MATMPIDENSE, MATSEQBAIJ, MATMPIBAIJ, MATSEQSBAIJ, MATMPIBAIJ, ""));
3026:         if (flg) Bexp = B;
3027:         else {
3028:           /* If the "preconditioning" matrix is itself MATSHELL or some other type without direct support */
3029:           PetscCall(MatComputeOperator(B, MATAIJ, &Bexp_mine));
3030:           Bexp = Bexp_mine;
3031:         }
3032:       }
3033:       PetscCall(MatConvert(Bexp, MATSAME, MAT_INITIAL_MATRIX, &FDexp));
3034:       PetscCall(SNESComputeJacobianDefault(snes, X, FDexp, FDexp, NULL));
3035:       PetscCall(PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes), &vstdout));
3036:       if (flag_draw || flag_contour) {
3037:         PetscCall(PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes), NULL, "Explicit Jacobians", PETSC_DECIDE, PETSC_DECIDE, 300, 300, &vdraw));
3038:         if (flag_contour) PetscCall(PetscViewerPushFormat(vdraw, PETSC_VIEWER_DRAW_CONTOUR));
3039:       } else vdraw = NULL;
3040:       PetscCall(PetscViewerASCIIPrintf(vstdout, "Explicit %s\n", flag_operator ? "Jacobian" : "preconditioning Jacobian"));
3041:       if (flag) PetscCall(MatView(Bexp, vstdout));
3042:       if (vdraw) PetscCall(MatView(Bexp, vdraw));
3043:       PetscCall(PetscViewerASCIIPrintf(vstdout, "Finite difference Jacobian\n"));
3044:       if (flag) PetscCall(MatView(FDexp, vstdout));
3045:       if (vdraw) PetscCall(MatView(FDexp, vdraw));
3046:       PetscCall(MatAYPX(FDexp, -1.0, Bexp, SAME_NONZERO_PATTERN));
3047:       PetscCall(PetscViewerASCIIPrintf(vstdout, "User-provided matrix minus finite difference Jacobian\n"));
3048:       if (flag) PetscCall(MatView(FDexp, vstdout));
3049:       if (vdraw) { /* Always use contour for the difference */
3050:         PetscCall(PetscViewerPushFormat(vdraw, PETSC_VIEWER_DRAW_CONTOUR));
3051:         PetscCall(MatView(FDexp, vdraw));
3052:         PetscCall(PetscViewerPopFormat(vdraw));
3053:       }
3054:       if (flag_contour) PetscCall(PetscViewerPopFormat(vdraw));
3055:       PetscCall(PetscViewerDestroy(&vdraw));
3056:       PetscCall(MatDestroy(&Bexp_mine));
3057:       PetscCall(MatDestroy(&FDexp));
3058:     }
3059:   }
3060:   {
3061:     PetscBool flag = PETSC_FALSE, flag_display = PETSC_FALSE, flag_draw = PETSC_FALSE, flag_contour = PETSC_FALSE, flag_threshold = PETSC_FALSE;
3062:     PetscReal threshold_atol = PETSC_SQRT_MACHINE_EPSILON, threshold_rtol = 10 * PETSC_SQRT_MACHINE_EPSILON;
3063:     PetscCall(PetscOptionsCreateViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_compare_coloring", NULL, NULL, &flag));
3064:     PetscCall(PetscOptionsCreateViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_compare_coloring_display", NULL, NULL, &flag_display));
3065:     PetscCall(PetscOptionsCreateViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_compare_coloring_draw", NULL, NULL, &flag_draw));
3066:     PetscCall(PetscOptionsCreateViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_compare_coloring_draw_contour", NULL, NULL, &flag_contour));
3067:     PetscCall(PetscOptionsCreateViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_compare_coloring_threshold", NULL, NULL, &flag_threshold));
3068:     if (flag_threshold) {
3069:       PetscCall(PetscOptionsGetReal(((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_compare_coloring_threshold_rtol", &threshold_rtol, NULL));
3070:       PetscCall(PetscOptionsGetReal(((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_compare_coloring_threshold_atol", &threshold_atol, NULL));
3071:     }
3072:     if (flag || flag_display || flag_draw || flag_contour || flag_threshold) {
3073:       Mat             Bfd;
3074:       PetscViewer     vdraw, vstdout;
3075:       MatColoring     coloring;
3076:       ISColoring      iscoloring;
3077:       MatFDColoring   matfdcoloring;
3078:       SNESFunctionFn *func;
3079:       void           *funcctx;
3080:       PetscReal       norm1, norm2, normmax;
3082:       PetscCall(MatDuplicate(B, MAT_DO_NOT_COPY_VALUES, &Bfd));
3083:       PetscCall(MatColoringCreate(Bfd, &coloring));
3084:       PetscCall(MatColoringSetType(coloring, MATCOLORINGSL));
3085:       PetscCall(MatColoringSetFromOptions(coloring));
3086:       PetscCall(MatColoringApply(coloring, &iscoloring));
3087:       PetscCall(MatColoringDestroy(&coloring));
3088:       PetscCall(MatFDColoringCreate(Bfd, iscoloring, &matfdcoloring));
3089:       PetscCall(MatFDColoringSetFromOptions(matfdcoloring));
3090:       PetscCall(MatFDColoringSetUp(Bfd, iscoloring, matfdcoloring));
3091:       PetscCall(ISColoringDestroy(&iscoloring));
3093:       /* This method of getting the function is currently unreliable since it doesn't work for DM local functions. */
3094:       PetscCall(SNESGetFunction(snes, NULL, &func, &funcctx));
3095:       PetscCall(MatFDColoringSetFunction(matfdcoloring, (PetscErrorCode (*)(void))func, funcctx));
3096:       PetscCall(PetscObjectSetOptionsPrefix((PetscObject)matfdcoloring, ((PetscObject)snes)->prefix));
3097:       PetscCall(PetscObjectAppendOptionsPrefix((PetscObject)matfdcoloring, "coloring_"));
3098:       PetscCall(MatFDColoringSetFromOptions(matfdcoloring));
3099:       PetscCall(MatFDColoringApply(Bfd, matfdcoloring, X, snes));
3100:       PetscCall(MatFDColoringDestroy(&matfdcoloring));
3102:       PetscCall(PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes), &vstdout));
3103:       if (flag_draw || flag_contour) {
3104:         PetscCall(PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes), NULL, "Colored Jacobians", PETSC_DECIDE, PETSC_DECIDE, 300, 300, &vdraw));
3105:         if (flag_contour) PetscCall(PetscViewerPushFormat(vdraw, PETSC_VIEWER_DRAW_CONTOUR));
3106:       } else vdraw = NULL;
3107:       PetscCall(PetscViewerASCIIPrintf(vstdout, "Explicit preconditioning Jacobian\n"));
3108:       if (flag_display) PetscCall(MatView(B, vstdout));
3109:       if (vdraw) PetscCall(MatView(B, vdraw));
3110:       PetscCall(PetscViewerASCIIPrintf(vstdout, "Colored Finite difference Jacobian\n"));
3111:       if (flag_display) PetscCall(MatView(Bfd, vstdout));
3112:       if (vdraw) PetscCall(MatView(Bfd, vdraw));
3113:       PetscCall(MatAYPX(Bfd, -1.0, B, SAME_NONZERO_PATTERN));
3114:       PetscCall(MatNorm(Bfd, NORM_1, &norm1));
3115:       PetscCall(MatNorm(Bfd, NORM_FROBENIUS, &norm2));
3116:       PetscCall(MatNorm(Bfd, NORM_MAX, &normmax));
3117:       PetscCall(PetscViewerASCIIPrintf(vstdout, "User-provided matrix minus finite difference Jacobian, norm1=%g normFrob=%g normmax=%g\n", (double)norm1, (double)norm2, (double)normmax));
3118:       if (flag_display) PetscCall(MatView(Bfd, vstdout));
3119:       if (vdraw) { /* Always use contour for the difference */
3120:         PetscCall(PetscViewerPushFormat(vdraw, PETSC_VIEWER_DRAW_CONTOUR));
3121:         PetscCall(MatView(Bfd, vdraw));
3122:         PetscCall(PetscViewerPopFormat(vdraw));
3123:       }
3124:       if (flag_contour) PetscCall(PetscViewerPopFormat(vdraw));
3126:       if (flag_threshold) {
3127:         PetscInt bs, rstart, rend, i;
3128:         PetscCall(MatGetBlockSize(B, &bs));
3129:         PetscCall(MatGetOwnershipRange(B, &rstart, &rend));
3130:         for (i = rstart; i < rend; i++) {
3131:           const PetscScalar *ba, *ca;
3132:           const PetscInt    *bj, *cj;
3133:           PetscInt           bn, cn, j, maxentrycol = -1, maxdiffcol = -1, maxrdiffcol = -1;
3134:           PetscReal          maxentry = 0, maxdiff = 0, maxrdiff = 0;
3135:           PetscCall(MatGetRow(B, i, &bn, &bj, &ba));
3136:           PetscCall(MatGetRow(Bfd, i, &cn, &cj, &ca));
3137:           PetscCheck(bn == cn, ((PetscObject)A)->comm, PETSC_ERR_PLIB, "Unexpected different nonzero pattern in -snes_compare_coloring_threshold");
3138:           for (j = 0; j < bn; j++) {
3139:             PetscReal rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol * PetscAbsScalar(ba[j]));
3140:             if (PetscAbsScalar(ba[j]) > PetscAbs(maxentry)) {
3141:               maxentrycol = bj[j];
3142:               maxentry    = PetscRealPart(ba[j]);
3143:             }
3144:             if (PetscAbsScalar(ca[j]) > PetscAbs(maxdiff)) {
3145:               maxdiffcol = bj[j];
3146:               maxdiff    = PetscRealPart(ca[j]);
3147:             }
3148:             if (rdiff > maxrdiff) {
3149:               maxrdiffcol = bj[j];
3150:               maxrdiff    = rdiff;
3151:             }
3152:           }
3153:           if (maxrdiff > 1) {
3154:             PetscCall(PetscViewerASCIIPrintf(vstdout, "row %" PetscInt_FMT " (maxentry=%g at %" PetscInt_FMT ", maxdiff=%g at %" PetscInt_FMT ", maxrdiff=%g at %" PetscInt_FMT "):", i, (double)maxentry, maxentrycol, (double)maxdiff, maxdiffcol, (double)maxrdiff, maxrdiffcol));
3155:             for (j = 0; j < bn; j++) {
3156:               PetscReal rdiff;
3157:               rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol * PetscAbsScalar(ba[j]));
3158:               if (rdiff > 1) PetscCall(PetscViewerASCIIPrintf(vstdout, " (%" PetscInt_FMT ",%g:%g)", bj[j], (double)PetscRealPart(ba[j]), (double)PetscRealPart(ca[j])));
3159:             }
3160:             PetscCall(PetscViewerASCIIPrintf(vstdout, "\n"));
3161:           }
3162:           PetscCall(MatRestoreRow(B, i, &bn, &bj, &ba));
3163:           PetscCall(MatRestoreRow(Bfd, i, &cn, &cj, &ca));
3164:         }
3165:       }
3166:       PetscCall(PetscViewerDestroy(&vdraw));
3167:       PetscCall(MatDestroy(&Bfd));
3168:     }
3169:   }
3170:   PetscFunctionReturn(PETSC_SUCCESS);
3171: }
3173: /*@C
3174:   SNESSetJacobian - Sets the function to compute Jacobian as well as the
3175:   location to store the matrix.
3177:   Logically Collective
3179:   Input Parameters:
3180: + snes - the `SNES` context
3181: . Amat - the matrix that defines the (approximate) Jacobian
3182: . Pmat - the matrix to be used in constructing the preconditioner, usually the same as `Amat`.
3183: . J    - Jacobian evaluation routine (if `NULL` then `SNES` retains any previously set value), see `SNESJacobianFn` for details
3184: - ctx  - [optional] user-defined context for private data for the
3185:          Jacobian evaluation routine (may be `NULL`) (if `NULL` then `SNES` retains any previously set value)
3187:   Level: beginner
3189:   Notes:
3190:   If the `Amat` matrix and `Pmat` matrix are different you must call `MatAssemblyBegin()`/`MatAssemblyEnd()` on
3191:   each matrix.
3193:   If you know the operator `Amat` has a null space you can use `MatSetNullSpace()` and `MatSetTransposeNullSpace()` to supply the null
3194:   space to `Amat` and the `KSP` solvers will automatically use that null space as needed during the solution process.
3196:   If using `SNESComputeJacobianDefaultColor()` to assemble a Jacobian, the `ctx` argument
3197:   must be a `MatFDColoring`.
3199:   Other defect-correction schemes can be used by computing a different matrix in place of the Jacobian.  One common
3200:   example is to use the "Picard linearization" which only differentiates through the highest order parts of each term using `SNESSetPicard()`
3202: .seealso: [](ch_snes), `SNES`, `KSPSetOperators()`, `SNESSetFunction()`, `MatMFFDComputeJacobian()`, `SNESComputeJacobianDefaultColor()`, `MatStructure`,
3203:           `SNESSetPicard()`, `SNESJacobianFn`, `SNESFunctionFn`
3204: @*/
3205: PetscErrorCode SNESSetJacobian(SNES snes, Mat Amat, Mat Pmat, SNESJacobianFn *J, void *ctx)
3206: {
3207:   DM dm;
3209:   PetscFunctionBegin;
3213:   if (Amat) PetscCheckSameComm(snes, 1, Amat, 2);
3214:   if (Pmat) PetscCheckSameComm(snes, 1, Pmat, 3);
3215:   PetscCall(SNESGetDM(snes, &dm));
3216:   PetscCall(DMSNESSetJacobian(dm, J, ctx));
3217:   if (Amat) {
3218:     PetscCall(PetscObjectReference((PetscObject)Amat));
3219:     PetscCall(MatDestroy(&snes->jacobian));
3221:     snes->jacobian = Amat;
3222:   }
3223:   if (Pmat) {
3224:     PetscCall(PetscObjectReference((PetscObject)Pmat));
3225:     PetscCall(MatDestroy(&snes->jacobian_pre));
3227:     snes->jacobian_pre = Pmat;
3228:   }
3229:   PetscFunctionReturn(PETSC_SUCCESS);
3230: }
3232: /*@C
3233:   SNESGetJacobian - Returns the Jacobian matrix and optionally the user
3234:   provided context for evaluating the Jacobian.
3236:   Not Collective, but `Mat` object will be parallel if `SNES` is
3238:   Input Parameter:
3239: . snes - the nonlinear solver context
3241:   Output Parameters:
3242: + Amat - location to stash (approximate) Jacobian matrix (or `NULL`)
3243: . Pmat - location to stash matrix used to compute the preconditioner (or `NULL`)
3244: . J    - location to put Jacobian function (or `NULL`), for calling sequence see `SNESJacobianFn`
3245: - ctx  - location to stash Jacobian ctx (or `NULL`)
3247:   Level: advanced
3249: .seealso: [](ch_snes), `SNES`, `Mat`, `SNESSetJacobian()`, `SNESComputeJacobian()`, `SNESJacobianFn`, `SNESGetFunction()`
3250: @*/
3251: PetscErrorCode SNESGetJacobian(SNES snes, Mat *Amat, Mat *Pmat, SNESJacobianFn **J, void **ctx)
3252: {
3253:   DM dm;
3255:   PetscFunctionBegin;
3257:   if (Amat) *Amat = snes->jacobian;
3258:   if (Pmat) *Pmat = snes->jacobian_pre;
3259:   PetscCall(SNESGetDM(snes, &dm));
3260:   PetscCall(DMSNESGetJacobian(dm, J, ctx));
3261:   PetscFunctionReturn(PETSC_SUCCESS);
3262: }
3264: static PetscErrorCode SNESSetDefaultComputeJacobian(SNES snes)
3265: {
3266:   DM     dm;
3267:   DMSNES sdm;
3269:   PetscFunctionBegin;
3270:   PetscCall(SNESGetDM(snes, &dm));
3271:   PetscCall(DMGetDMSNES(dm, &sdm));
3272:   if (!sdm->ops->computejacobian && snes->jacobian_pre) {
3273:     DM        dm;
3274:     PetscBool isdense, ismf;
3276:     PetscCall(SNESGetDM(snes, &dm));
3277:     PetscCall(PetscObjectTypeCompareAny((PetscObject)snes->jacobian_pre, &isdense, MATSEQDENSE, MATMPIDENSE, MATDENSE, NULL));
3278:     PetscCall(PetscObjectTypeCompareAny((PetscObject)snes->jacobian_pre, &ismf, MATMFFD, MATSHELL, NULL));
3279:     if (isdense) {
3280:       PetscCall(DMSNESSetJacobian(dm, SNESComputeJacobianDefault, NULL));
3281:     } else if (!ismf) {
3282:       PetscCall(DMSNESSetJacobian(dm, SNESComputeJacobianDefaultColor, NULL));
3283:     }
3284:   }
3285:   PetscFunctionReturn(PETSC_SUCCESS);
3286: }
3288: /*@
3289:   SNESSetUp - Sets up the internal data structures for the later use
3290:   of a nonlinear solver `SNESSolve()`.
3292:   Collective
3294:   Input Parameter:
3295: . snes - the `SNES` context
3297:   Level: advanced
3299:   Note:
3300:   For basic use of the `SNES` solvers the user does not need to explicitly call
3301:   `SNESSetUp()`, since these actions will automatically occur during
3302:   the call to `SNESSolve()`.  However, if one wishes to control this
3303:   phase separately, `SNESSetUp()` should be called after `SNESCreate()`
3304:   and optional routines of the form SNESSetXXX(), but before `SNESSolve()`.
3306: .seealso: [](ch_snes), `SNES`, `SNESCreate()`, `SNESSolve()`, `SNESDestroy()`, `SNESSetFromOptions()`
3307: @*/
3308: PetscErrorCode SNESSetUp(SNES snes)
3309: {
3310:   DM             dm;
3311:   DMSNES         sdm;
3312:   SNESLineSearch linesearch, pclinesearch;
3313:   void          *lsprectx, *lspostctx;
3314:   PetscBool      mf_operator, mf;
3315:   Vec            f, fpc;
3316:   void          *funcctx;
3317:   void          *jacctx, *appctx;
3318:   Mat            j, jpre;
3319:   PetscErrorCode (*precheck)(SNESLineSearch, Vec, Vec, PetscBool *, void *);
3320:   PetscErrorCode (*postcheck)(SNESLineSearch, Vec, Vec, Vec, PetscBool *, PetscBool *, void *);
3321:   SNESFunctionFn *func;
3322:   SNESJacobianFn *jac;
3324:   PetscFunctionBegin;
3326:   if (snes->setupcalled) PetscFunctionReturn(PETSC_SUCCESS);
3327:   PetscCall(PetscLogEventBegin(SNES_SetUp, snes, 0, 0, 0));
3329:   if (!((PetscObject)snes)->type_name) PetscCall(SNESSetType(snes, SNESNEWTONLS));
3331:   PetscCall(SNESGetFunction(snes, &snes->vec_func, NULL, NULL));
3333:   PetscCall(SNESGetDM(snes, &dm));
3334:   PetscCall(DMGetDMSNES(dm, &sdm));
3335:   PetscCall(SNESSetDefaultComputeJacobian(snes));
3337:   if (!snes->vec_func) PetscCall(DMCreateGlobalVector(dm, &snes->vec_func));
3339:   if (!snes->ksp) PetscCall(SNESGetKSP(snes, &snes->ksp));
3341:   if (snes->linesearch) {
3342:     PetscCall(SNESGetLineSearch(snes, &snes->linesearch));
3343:     PetscCall(SNESLineSearchSetFunction(snes->linesearch, SNESComputeFunction));
3344:   }
3346:   PetscCall(SNESGetUseMatrixFree(snes, &mf_operator, &mf));
3347:   if (snes->npc && snes->npcside == PC_LEFT) {
3348:     snes->mf          = PETSC_TRUE;
3349:     snes->mf_operator = PETSC_FALSE;
3350:   }
3352:   if (snes->npc) {
3353:     /* copy the DM over */
3354:     PetscCall(SNESGetDM(snes, &dm));
3355:     PetscCall(SNESSetDM(snes->npc, dm));
3357:     PetscCall(SNESGetFunction(snes, &f, &func, &funcctx));
3358:     PetscCall(VecDuplicate(f, &fpc));
3359:     PetscCall(SNESSetFunction(snes->npc, fpc, func, funcctx));
3360:     PetscCall(SNESGetJacobian(snes, &j, &jpre, &jac, &jacctx));
3361:     PetscCall(SNESSetJacobian(snes->npc, j, jpre, jac, jacctx));
3362:     PetscCall(SNESGetApplicationContext(snes, &appctx));
3363:     PetscCall(SNESSetApplicationContext(snes->npc, appctx));
3364:     PetscCall(SNESSetUseMatrixFree(snes->npc, mf_operator, mf));
3365:     PetscCall(VecDestroy(&fpc));
3367:     /* copy the function pointers over */
3368:     PetscCall(PetscObjectCopyFortranFunctionPointers((PetscObject)snes, (PetscObject)snes->npc));
3370:     /* default to 1 iteration */
3371:     PetscCall(SNESSetTolerances(snes->npc, 0.0, 0.0, 0.0, 1, snes->npc->max_funcs));
3372:     if (snes->npcside == PC_RIGHT) {
3373:       PetscCall(SNESSetNormSchedule(snes->npc, SNES_NORM_FINAL_ONLY));
3374:     } else {
3375:       PetscCall(SNESSetNormSchedule(snes->npc, SNES_NORM_NONE));
3376:     }
3377:     PetscCall(SNESSetFromOptions(snes->npc));
3379:     /* copy the line search context over */
3380:     if (snes->linesearch && snes->npc->linesearch) {
3381:       PetscCall(SNESGetLineSearch(snes, &linesearch));
3382:       PetscCall(SNESGetLineSearch(snes->npc, &pclinesearch));
3383:       PetscCall(SNESLineSearchGetPreCheck(linesearch, &precheck, &lsprectx));
3384:       PetscCall(SNESLineSearchGetPostCheck(linesearch, &postcheck, &lspostctx));
3385:       PetscCall(SNESLineSearchSetPreCheck(pclinesearch, precheck, lsprectx));
3386:       PetscCall(SNESLineSearchSetPostCheck(pclinesearch, postcheck, lspostctx));
3387:       PetscCall(PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)pclinesearch));
3388:     }
3389:   }
3390:   if (snes->mf) PetscCall(SNESSetUpMatrixFree_Private(snes, snes->mf_operator, snes->mf_version));
3391:   if (snes->ops->usercompute && !snes->user) PetscCallBack("SNES callback compute application context", (*snes->ops->usercompute)(snes, (void **)&snes->user));
3393:   snes->jac_iter = 0;
3394:   snes->pre_iter = 0;
3396:   PetscTryTypeMethod(snes, setup);
3398:   PetscCall(SNESSetDefaultComputeJacobian(snes));
3400:   if (snes->npc && snes->npcside == PC_LEFT) {
3401:     if (snes->functype == SNES_FUNCTION_PRECONDITIONED) {
3402:       if (snes->linesearch) {
3403:         PetscCall(SNESGetLineSearch(snes, &linesearch));
3404:         PetscCall(SNESLineSearchSetFunction(linesearch, SNESComputeFunctionDefaultNPC));
3405:       }
3406:     }
3407:   }
3408:   PetscCall(PetscLogEventEnd(SNES_SetUp, snes, 0, 0, 0));
3409:   snes->setupcalled = PETSC_TRUE;
3410:   PetscFunctionReturn(PETSC_SUCCESS);
3411: }
3413: /*@
3414:   SNESReset - Resets a `SNES` context to the state it was in before `SNESSetUp()` was called and removes any allocated `Vec` and `Mat` from its data structures
3416:   Collective
3418:   Input Parameter:
3419: . snes - the nonlinear iterative solver context obtained from `SNESCreate()`
3421:   Level: intermediate
3423:   Notes:
3424:   Any options set on the `SNES` object, including those set with `SNESSetFromOptions()` remain.
3426:   Call this if you wish to reuse a `SNES` but with different size vectors
3428:   Also calls the application context destroy routine set with `SNESSetComputeApplicationContext()`
3430: .seealso: [](ch_snes), `SNES`, `SNESDestroy()`, `SNESCreate()`, `SNESSetUp()`, `SNESSolve()`
3431: @*/
3432: PetscErrorCode SNESReset(SNES snes)
3433: {
3434:   PetscFunctionBegin;
3436:   if (snes->ops->userdestroy && snes->user) {
3437:     PetscCallBack("SNES callback destroy application context", (*snes->ops->userdestroy)((void **)&snes->user));
3438:     snes->user = NULL;
3439:   }
3440:   if (snes->npc) PetscCall(SNESReset(snes->npc));
3442:   PetscTryTypeMethod(snes, reset);
3443:   if (snes->ksp) PetscCall(KSPReset(snes->ksp));
3445:   if (snes->linesearch) PetscCall(SNESLineSearchReset(snes->linesearch));
3447:   PetscCall(VecDestroy(&snes->vec_rhs));
3448:   PetscCall(VecDestroy(&snes->vec_sol));
3449:   PetscCall(VecDestroy(&snes->vec_sol_update));
3450:   PetscCall(VecDestroy(&snes->vec_func));
3451:   PetscCall(MatDestroy(&snes->jacobian));
3452:   PetscCall(MatDestroy(&snes->jacobian_pre));
3453:   PetscCall(MatDestroy(&snes->picard));
3454:   PetscCall(VecDestroyVecs(snes->nwork, &snes->work));
3455:   PetscCall(VecDestroyVecs(snes->nvwork, &snes->vwork));
3457:   snes->alwayscomputesfinalresidual = PETSC_FALSE;
3459:   snes->nwork = snes->nvwork = 0;
3460:   snes->setupcalled          = PETSC_FALSE;
3461:   PetscFunctionReturn(PETSC_SUCCESS);
3462: }
3464: /*@
3465:   SNESConvergedReasonViewCancel - Clears all the reason view functions for a `SNES` object provided with `SNESConvergedReasonViewSet()` also
3466:   removes the default viewer.
3468:   Collective
3470:   Input Parameter:
3471: . snes - the nonlinear iterative solver context obtained from `SNESCreate()`
3473:   Level: intermediate
3475: .seealso: [](ch_snes), `SNES`, `SNESCreate()`, `SNESDestroy()`, `SNESReset()`, `SNESConvergedReasonViewSet()`
3476: @*/
3477: PetscErrorCode SNESConvergedReasonViewCancel(SNES snes)
3478: {
3479:   PetscInt i;
3481:   PetscFunctionBegin;
3483:   for (i = 0; i < snes->numberreasonviews; i++) {
3484:     if (snes->reasonviewdestroy[i]) PetscCall((*snes->reasonviewdestroy[i])(&snes->reasonviewcontext[i]));
3485:   }
3486:   snes->numberreasonviews = 0;
3487:   PetscCall(PetscViewerDestroy(&snes->convergedreasonviewer));
3488:   PetscFunctionReturn(PETSC_SUCCESS);
3489: }
3491: /*@
3492:   SNESDestroy - Destroys the nonlinear solver context that was created
3493:   with `SNESCreate()`.
3495:   Collective
3497:   Input Parameter:
3498: . snes - the `SNES` context
3500:   Level: beginner
3502: .seealso: [](ch_snes), `SNES`, `SNESCreate()`, `SNESSolve()`
3503: @*/
3504: PetscErrorCode SNESDestroy(SNES *snes)
3505: {
3506:   PetscFunctionBegin;
3507:   if (!*snes) PetscFunctionReturn(PETSC_SUCCESS);
3509:   if (--((PetscObject)*snes)->refct > 0) {
3510:     *snes = NULL;
3511:     PetscFunctionReturn(PETSC_SUCCESS);
3512:   }
3514:   PetscCall(SNESReset(*snes));
3515:   PetscCall(SNESDestroy(&(*snes)->npc));
3517:   /* if memory was published with SAWs then destroy it */
3518:   PetscCall(PetscObjectSAWsViewOff((PetscObject)*snes));
3519:   PetscTryTypeMethod(*snes, destroy);
3521:   if ((*snes)->dm) PetscCall(DMCoarsenHookRemove((*snes)->dm, DMCoarsenHook_SNESVecSol, DMRestrictHook_SNESVecSol, *snes));
3522:   PetscCall(DMDestroy(&(*snes)->dm));
3523:   PetscCall(KSPDestroy(&(*snes)->ksp));
3524:   PetscCall(SNESLineSearchDestroy(&(*snes)->linesearch));
3526:   PetscCall(PetscFree((*snes)->kspconvctx));
3527:   if ((*snes)->ops->convergeddestroy) PetscCall((*(*snes)->ops->convergeddestroy)((*snes)->cnvP));
3528:   if ((*snes)->conv_hist_alloc) PetscCall(PetscFree2((*snes)->conv_hist, (*snes)->conv_hist_its));
3529:   PetscCall(SNESMonitorCancel(*snes));
3530:   PetscCall(SNESConvergedReasonViewCancel(*snes));
3531:   PetscCall(PetscHeaderDestroy(snes));
3532:   PetscFunctionReturn(PETSC_SUCCESS);
3533: }
3535: /* ----------- Routines to set solver parameters ---------- */
3537: /*@
3538:   SNESSetLagPreconditioner - Sets when the preconditioner is rebuilt in the nonlinear solve `SNESSolve()`.
3540:   Logically Collective
3542:   Input Parameters:
3543: + snes - the `SNES` context
3544: - lag  - 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3545:          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that
3547:   Options Database Keys:
3548: + -snes_lag_jacobian_persists <true,false>       - sets the persistence through multiple `SNESSolve()`
3549: . -snes_lag_jacobian <-2,1,2,...>                - sets the lag
3550: . -snes_lag_preconditioner_persists <true,false> - sets the persistence through multiple `SNESSolve()`
3551: - -snes_lag_preconditioner <-2,1,2,...>          - sets the lag
3553:   Level: intermediate
3555:   Notes:
3556:   The default is 1
3558:   The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1 or `SNESSetLagPreconditionerPersists()` was called
3560:   `SNESSetLagPreconditionerPersists()` allows using the same uniform lagging (for example every second linear solve) across multiple nonlinear solves.
3562: .seealso: [](ch_snes), `SNESGetLagPreconditioner()`, `SNESSetLagJacobian()`, `SNESGetLagJacobian()`, `SNESSetLagPreconditionerPersists()`,
3563:           `SNESSetLagJacobianPersists()`, `SNES`, `SNESSolve()`
3564: @*/
3565: PetscErrorCode SNESSetLagPreconditioner(SNES snes, PetscInt lag)
3566: {
3567:   PetscFunctionBegin;
3569:   PetscCheck(lag >= -2, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Lag must be -2, -1, 1 or greater");
3570:   PetscCheck(lag, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Lag cannot be 0");
3572:   snes->lagpreconditioner = lag;
3573:   PetscFunctionReturn(PETSC_SUCCESS);
3574: }
3576: /*@
3577:   SNESSetGridSequence - sets the number of steps of grid sequencing that `SNES` will do
3579:   Logically Collective
3581:   Input Parameters:
3582: + snes  - the `SNES` context
3583: - steps - the number of refinements to do, defaults to 0
3585:   Options Database Key:
3586: . -snes_grid_sequence <steps> - Use grid sequencing to generate initial guess
3588:   Level: intermediate
3590:   Notes:
3591:   Once grid sequencing is turned on `SNESSolve()` will automatically perform the solve on each grid refinement.
3593:   Use `SNESGetSolution()` to extract the fine grid solution after grid sequencing.
3595: .seealso: [](ch_snes), `SNES`, `SNESGetLagPreconditioner()`, `SNESSetLagJacobian()`, `SNESGetLagJacobian()`, `SNESGetGridSequence()`,
3596:           `SNESSetDM()`, `SNESSolve()`
3597: @*/
3598: PetscErrorCode SNESSetGridSequence(SNES snes, PetscInt steps)
3599: {
3600:   PetscFunctionBegin;
3603:   snes->gridsequence = steps;
3604:   PetscFunctionReturn(PETSC_SUCCESS);
3605: }
3607: /*@
3608:   SNESGetGridSequence - gets the number of steps of grid sequencing that `SNES` will do
3610:   Logically Collective
3612:   Input Parameter:
3613: . snes - the `SNES` context
3615:   Output Parameter:
3616: . steps - the number of refinements to do, defaults to 0
3618:   Level: intermediate
3620: .seealso: [](ch_snes), `SNESGetLagPreconditioner()`, `SNESSetLagJacobian()`, `SNESGetLagJacobian()`, `SNESSetGridSequence()`
3621: @*/
3622: PetscErrorCode SNESGetGridSequence(SNES snes, PetscInt *steps)
3623: {
3624:   PetscFunctionBegin;
3626:   *steps = snes->gridsequence;
3627:   PetscFunctionReturn(PETSC_SUCCESS);
3628: }
3630: /*@
3631:   SNESGetLagPreconditioner - Return how often the preconditioner is rebuilt
3633:   Not Collective
3635:   Input Parameter:
3636: . snes - the `SNES` context
3638:   Output Parameter:
3639: . lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3640:          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that
3642:   Level: intermediate
3644:   Notes:
3645:   The default is 1
3647:   The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
3649: .seealso: [](ch_snes), `SNES`, `SNESSetLagPreconditioner()`, `SNESSetLagJacobianPersists()`, `SNESSetLagPreconditionerPersists()`
3650: @*/
3651: PetscErrorCode SNESGetLagPreconditioner(SNES snes, PetscInt *lag)
3652: {
3653:   PetscFunctionBegin;
3655:   *lag = snes->lagpreconditioner;
3656:   PetscFunctionReturn(PETSC_SUCCESS);
3657: }
3659: /*@
3660:   SNESSetLagJacobian - Set when the Jacobian is rebuilt in the nonlinear solve. See `SNESSetLagPreconditioner()` for determining how
3661:   often the preconditioner is rebuilt.
3663:   Logically Collective
3665:   Input Parameters:
3666: + snes - the `SNES` context
3667: - lag  - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3668:          the Jacobian is built etc. -2 means rebuild at next chance but then never again
3670:   Options Database Keys:
3671: + -snes_lag_jacobian_persists <true,false>       - sets the persistence through multiple SNES solves
3672: . -snes_lag_jacobian <-2,1,2,...>                - sets the lag
3673: . -snes_lag_preconditioner_persists <true,false> - sets the persistence through multiple SNES solves
3674: - -snes_lag_preconditioner <-2,1,2,...>          - sets the lag.
3676:   Level: intermediate
3678:   Notes:
3679:   The default is 1
3681:   The Jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
3683:   If  -1 is used before the very first nonlinear solve the CODE WILL FAIL! because no Jacobian is used, use -2 to indicate you want it recomputed
3684:   at the next Newton step but never again (unless it is reset to another value)
3686: .seealso: [](ch_snes), `SNES`, `SNESGetLagPreconditioner()`, `SNESSetLagPreconditioner()`, `SNESGetLagJacobianPersists()`, `SNESSetLagPreconditionerPersists()`
3687: @*/
3688: PetscErrorCode SNESSetLagJacobian(SNES snes, PetscInt lag)
3689: {
3690:   PetscFunctionBegin;
3692:   PetscCheck(lag >= -2, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Lag must be -2, -1, 1 or greater");
3693:   PetscCheck(lag, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Lag cannot be 0");
3695:   snes->lagjacobian = lag;
3696:   PetscFunctionReturn(PETSC_SUCCESS);
3697: }
3699: /*@
3700:   SNESGetLagJacobian - Get how often the Jacobian is rebuilt. See `SNESGetLagPreconditioner()` to determine when the preconditioner is rebuilt
3702:   Not Collective
3704:   Input Parameter:
3705: . snes - the `SNES` context
3707:   Output Parameter:
3708: . lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3709:          the Jacobian is built etc.
3711:   Level: intermediate
3713:   Notes:
3714:   The default is 1
3716:   The jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1 or `SNESSetLagJacobianPersists()` was called.
3718: .seealso: [](ch_snes), `SNES`, `SNESSetLagJacobian()`, `SNESSetLagPreconditioner()`, `SNESGetLagPreconditioner()`, `SNESSetLagJacobianPersists()`, `SNESSetLagPreconditionerPersists()`
3720: @*/
3721: PetscErrorCode SNESGetLagJacobian(SNES snes, PetscInt *lag)
3722: {
3723:   PetscFunctionBegin;
3725:   *lag = snes->lagjacobian;
3726:   PetscFunctionReturn(PETSC_SUCCESS);
3727: }
3729: /*@
3730:   SNESSetLagJacobianPersists - Set whether or not the Jacobian lagging persists through multiple nonlinear solves
3732:   Logically collective
3734:   Input Parameters:
3735: + snes - the `SNES` context
3736: - flg  - jacobian lagging persists if true
3738:   Options Database Keys:
3739: + -snes_lag_jacobian_persists <true,false>       - sets the persistence through multiple SNES solves
3740: . -snes_lag_jacobian <-2,1,2,...>                - sets the lag
3741: . -snes_lag_preconditioner_persists <true,false> - sets the persistence through multiple SNES solves
3742: - -snes_lag_preconditioner <-2,1,2,...>          - sets the lag
3744:   Level: advanced
3746:   Notes:
3747:   Normally when `SNESSetLagJacobian()` is used, the Jacobian is always rebuilt at the beginning of each new nonlinear solve, this removes that behavior
3749:   This is useful both for nonlinear preconditioning, where it's appropriate to have the Jacobian be stale by
3750:   several solves, and for implicit time-stepping, where Jacobian lagging in the inner nonlinear solve over several
3751:   timesteps may present huge efficiency gains.
3753: .seealso: [](ch_snes), `SNES`, `SNESSetLagPreconditionerPersists()`, `SNESSetLagJacobian()`, `SNESGetLagJacobian()`, `SNESGetNPC()`
3754: @*/
3755: PetscErrorCode SNESSetLagJacobianPersists(SNES snes, PetscBool flg)
3756: {
3757:   PetscFunctionBegin;
3760:   snes->lagjac_persist = flg;
3761:   PetscFunctionReturn(PETSC_SUCCESS);
3762: }
3764: /*@
3765:   SNESSetLagPreconditionerPersists - Set whether or not the preconditioner lagging persists through multiple nonlinear solves
3767:   Logically Collective
3769:   Input Parameters:
3770: + snes - the `SNES` context
3771: - flg  - preconditioner lagging persists if true
3773:   Options Database Keys:
3774: + -snes_lag_jacobian_persists <true,false>       - sets the persistence through multiple SNES solves
3775: . -snes_lag_jacobian <-2,1,2,...>                - sets the lag
3776: . -snes_lag_preconditioner_persists <true,false> - sets the persistence through multiple SNES solves
3777: - -snes_lag_preconditioner <-2,1,2,...>          - sets the lag
3779:   Level: developer
3781:   Notes:
3782:   Normally when `SNESSetLagPreconditioner()` is used, the preconditioner is always rebuilt at the beginning of each new nonlinear solve, this removes that behavior
3784:   This is useful both for nonlinear preconditioning, where it's appropriate to have the preconditioner be stale
3785:   by several solves, and for implicit time-stepping, where preconditioner lagging in the inner nonlinear solve over
3786:   several timesteps may present huge efficiency gains.
3788: .seealso: [](ch_snes), `SNES`, `SNESSetLagJacobianPersists()`, `SNESSetLagJacobian()`, `SNESGetLagJacobian()`, `SNESGetNPC()`, `SNESSetLagPreconditioner()`
3789: @*/
3790: PetscErrorCode SNESSetLagPreconditionerPersists(SNES snes, PetscBool flg)
3791: {
3792:   PetscFunctionBegin;
3795:   snes->lagpre_persist = flg;
3796:   PetscFunctionReturn(PETSC_SUCCESS);
3797: }
3799: /*@
3800:   SNESSetForceIteration - force `SNESSolve()` to take at least one iteration regardless of the initial residual norm
3802:   Logically Collective
3804:   Input Parameters:
3805: + snes  - the `SNES` context
3806: - force - `PETSC_TRUE` require at least one iteration
3808:   Options Database Key:
3809: . -snes_force_iteration <force> - Sets forcing an iteration
3811:   Level: intermediate
3813:   Note:
3814:   This is used sometimes with `TS` to prevent `TS` from detecting a false steady state solution
3816: .seealso: [](ch_snes), `SNES`, `TS`, `SNESSetDivergenceTolerance()`
3817: @*/
3818: PetscErrorCode SNESSetForceIteration(SNES snes, PetscBool force)
3819: {
3820:   PetscFunctionBegin;
3822:   snes->forceiteration = force;
3823:   PetscFunctionReturn(PETSC_SUCCESS);
3824: }
3826: /*@
3827:   SNESGetForceIteration - Check whether or not `SNESSolve()` take at least one iteration regardless of the initial residual norm
3829:   Logically Collective
3831:   Input Parameter:
3832: . snes - the `SNES` context
3834:   Output Parameter:
3835: . force - `PETSC_TRUE` requires at least one iteration.
3837:   Level: intermediate
3839: .seealso: [](ch_snes), `SNES`, `SNESSetForceIteration()`, `SNESSetDivergenceTolerance()`
3840: @*/
3841: PetscErrorCode SNESGetForceIteration(SNES snes, PetscBool *force)
3842: {
3843:   PetscFunctionBegin;
3845:   *force = snes->forceiteration;
3846:   PetscFunctionReturn(PETSC_SUCCESS);
3847: }
3849: /*@
3850:   SNESSetTolerances - Sets various parameters used in `SNES` convergence tests.
3852:   Logically Collective
3854:   Input Parameters:
3855: + snes   - the `SNES` context
3856: . abstol - the absolute convergence tolerance, $ F(x^n) \le abstol $
3857: . rtol   - the relative convergence tolerance, $ F(x^n) \le reltol * F(x^0) $
3858: . stol   - convergence tolerance in terms of the norm of the change in the solution between steps,  || delta x || < stol*|| x ||
3859: . maxit  - the maximum number of iterations allowed in the solver, default 50.
3860: - maxf   - the maximum number of function evaluations allowed in the solver (use `PETSC_UNLIMITED` indicates no limit), default 10,000
3862:   Options Database Keys:
3863: + -snes_atol <abstol>    - Sets `abstol`
3864: . -snes_rtol <rtol>      - Sets `rtol`
3865: . -snes_stol <stol>      - Sets `stol`
3866: . -snes_max_it <maxit>   - Sets `maxit`
3867: - -snes_max_funcs <maxf> - Sets `maxf` (use `unlimited` to have no maximum)
3869:   Level: intermediate
3871:   Note:
3872:   All parameters must be non-negative
3874:   Use `PETSC_CURRENT` to retain the current value of any parameter and `PETSC_DETERMINE` to use the default value for the given `SNES`.
3875:   The default value is the value in the object when its type is set.
3877:   Use `PETSC_UNLIMITED` on `maxit` or `maxf` to indicate there is no bound on the number of iterations or number of function evaluations.
3879:   Fortran Note:
3880:   Use `PETSC_CURRENT_INTEGER`, `PETSC_CURRENT_REAL`, `PETSC_UNLIMITED_INTEGER`, `PETSC_DETERMINE_INTEGER`, or `PETSC_DETERMINE_REAL`
3882: .seealso: [](ch_snes), `SNESSolve()`, `SNES`, `SNESSetDivergenceTolerance()`, `SNESSetForceIteration()`
3883: @*/
3884: PetscErrorCode SNESSetTolerances(SNES snes, PetscReal abstol, PetscReal rtol, PetscReal stol, PetscInt maxit, PetscInt maxf)
3885: {
3886:   PetscFunctionBegin;
3894:   if (abstol == (PetscReal)PETSC_DETERMINE) {
3895:     snes->abstol = snes->default_abstol;
3896:   } else if (abstol != (PetscReal)PETSC_CURRENT) {
3897:     PetscCheck(abstol >= 0.0, PetscObjectComm((PetscObject)snes), PETSC_ERR_ARG_OUTOFRANGE, "Absolute tolerance %g must be non-negative", (double)abstol);
3898:     snes->abstol = abstol;
3899:   }
3901:   if (rtol == (PetscReal)PETSC_DETERMINE) {
3902:     snes->rtol = snes->default_rtol;
3903:   } else if (rtol != (PetscReal)PETSC_CURRENT) {
3904:     PetscCheck(rtol >= 0.0 && 1.0 > rtol, PetscObjectComm((PetscObject)snes), PETSC_ERR_ARG_OUTOFRANGE, "Relative tolerance %g must be non-negative and less than 1.0", (double)rtol);
3905:     snes->rtol = rtol;
3906:   }
3908:   if (stol == (PetscReal)PETSC_DETERMINE) {
3909:     snes->stol = snes->default_stol;
3910:   } else if (stol != (PetscReal)PETSC_CURRENT) {
3911:     PetscCheck(stol >= 0.0, PetscObjectComm((PetscObject)snes), PETSC_ERR_ARG_OUTOFRANGE, "Step tolerance %g must be non-negative", (double)stol);
3912:     snes->stol = stol;
3913:   }
3915:   if (maxit == (PetscInt)PETSC_DETERMINE) {
3916:     snes->max_its = snes->default_max_its;
3917:   } else if (maxit == (PetscInt)PETSC_UNLIMITED) {
3918:     snes->max_its = PETSC_INT_MAX;
3919:   } else if (maxit != PETSC_CURRENT) {
3920:     PetscCheck(maxit >= 0, PetscObjectComm((PetscObject)snes), PETSC_ERR_ARG_OUTOFRANGE, "Maximum number of iterations %" PetscInt_FMT " must be non-negative", maxit);
3921:     snes->max_its = maxit;
3922:   }
3924:   if (maxf == (PetscInt)PETSC_DETERMINE) {
3925:     snes->max_funcs = snes->default_max_funcs;
3926:   } else if (maxf == (PetscInt)PETSC_UNLIMITED || maxf == -1) {
3927:     snes->max_funcs = PETSC_UNLIMITED;
3928:   } else if (maxf != PETSC_CURRENT) {
3929:     PetscCheck(maxf >= 0, PetscObjectComm((PetscObject)snes), PETSC_ERR_ARG_OUTOFRANGE, "Maximum number of function evaluations %" PetscInt_FMT " must be nonnegative", maxf);
3930:     snes->max_funcs = maxf;
3931:   }
3932:   PetscFunctionReturn(PETSC_SUCCESS);
3933: }
3935: /*@
3936:   SNESSetDivergenceTolerance - Sets the divergence tolerance used for the `SNES` divergence test.
3938:   Logically Collective
3940:   Input Parameters:
3941: + snes   - the `SNES` context
3942: - divtol - the divergence tolerance. Use `PETSC_UNLIMITED` to deactivate the test. If the residual norm $ F(x^n) \ge divtol * F(x^0) $ the solver
3943:            is stopped due to divergence.
3945:   Options Database Key:
3946: . -snes_divergence_tolerance <divtol> - Sets `divtol`
3948:   Level: intermediate
3950:   Notes:
3951:   Use `PETSC_DETERMINE` to use the default value from when the object's type was set.
3953:   Fortran Note:
3954:   Use ``PETSC_DETERMINE_REAL` or `PETSC_UNLIMITED_REAL`
3956: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESSetTolerances()`, `SNESGetDivergenceTolerance()`
3957: @*/
3958: PetscErrorCode SNESSetDivergenceTolerance(SNES snes, PetscReal divtol)
3959: {
3960:   PetscFunctionBegin;
3964:   if (divtol == (PetscReal)PETSC_DETERMINE) {
3965:     snes->divtol = snes->default_divtol;
3966:   } else if (divtol == (PetscReal)PETSC_UNLIMITED || divtol == -1) {
3967:     snes->divtol = PETSC_UNLIMITED;
3968:   } else if (divtol != (PetscReal)PETSC_CURRENT) {
3969:     PetscCheck(divtol >= 1.0, PetscObjectComm((PetscObject)snes), PETSC_ERR_ARG_OUTOFRANGE, "Divergence tolerance %g must be greater than 1.0", (double)divtol);
3970:     snes->divtol = divtol;
3971:   }
3972:   PetscFunctionReturn(PETSC_SUCCESS);
3973: }
3975: /*@
3976:   SNESGetTolerances - Gets various parameters used in `SNES` convergence tests.
3978:   Not Collective
3980:   Input Parameter:
3981: . snes - the `SNES` context
3983:   Output Parameters:
3984: + atol  - the absolute convergence tolerance
3985: . rtol  - the relative convergence tolerance
3986: . stol  - convergence tolerance in terms of the norm of the change in the solution between steps
3987: . maxit - the maximum number of iterations allowed
3988: - maxf  - the maximum number of function evaluations allowed, `PETSC_UNLIMITED` indicates no bound
3990:   Level: intermediate
3992:   Notes:
3993:   See `SNESSetTolerances()` for details on the parameters.
3995:   The user can specify `NULL` for any parameter that is not needed.
3997: .seealso: [](ch_snes), `SNES`, `SNESSetTolerances()`
3998: @*/
3999: PetscErrorCode SNESGetTolerances(SNES snes, PetscReal *atol, PetscReal *rtol, PetscReal *stol, PetscInt *maxit, PetscInt *maxf)
4000: {
4001:   PetscFunctionBegin;
4003:   if (atol) *atol = snes->abstol;
4004:   if (rtol) *rtol = snes->rtol;
4005:   if (stol) *stol = snes->stol;
4006:   if (maxit) *maxit = snes->max_its;
4007:   if (maxf) *maxf = snes->max_funcs;
4008:   PetscFunctionReturn(PETSC_SUCCESS);
4009: }
4011: /*@
4012:   SNESGetDivergenceTolerance - Gets divergence tolerance used in divergence test.
4014:   Not Collective
4016:   Input Parameters:
4017: + snes   - the `SNES` context
4018: - divtol - divergence tolerance
4020:   Level: intermediate
4022: .seealso: [](ch_snes), `SNES`, `SNESSetDivergenceTolerance()`
4023: @*/
4024: PetscErrorCode SNESGetDivergenceTolerance(SNES snes, PetscReal *divtol)
4025: {
4026:   PetscFunctionBegin;
4028:   if (divtol) *divtol = snes->divtol;
4029:   PetscFunctionReturn(PETSC_SUCCESS);
4030: }
4032: PETSC_INTERN PetscErrorCode SNESMonitorRange_Private(SNES, PetscInt, PetscReal *);
4034: PetscErrorCode SNESMonitorLGRange(SNES snes, PetscInt n, PetscReal rnorm, void *monctx)
4035: {
4036:   PetscDrawLG      lg;
4037:   PetscReal        x, y, per;
4038:   PetscViewer      v = (PetscViewer)monctx;
4039:   static PetscReal prev; /* should be in the context */
4040:   PetscDraw        draw;
4042:   PetscFunctionBegin;
4044:   PetscCall(PetscViewerDrawGetDrawLG(v, 0, &lg));
4045:   if (!n) PetscCall(PetscDrawLGReset(lg));
4046:   PetscCall(PetscDrawLGGetDraw(lg, &draw));
4047:   PetscCall(PetscDrawSetTitle(draw, "Residual norm"));
4048:   x = (PetscReal)n;
4049:   if (rnorm > 0.0) y = PetscLog10Real(rnorm);
4050:   else y = -15.0;
4051:   PetscCall(PetscDrawLGAddPoint(lg, &x, &y));
4052:   if (n < 20 || !(n % 5) || snes->reason) {
4053:     PetscCall(PetscDrawLGDraw(lg));
4054:     PetscCall(PetscDrawLGSave(lg));
4055:   }
4057:   PetscCall(PetscViewerDrawGetDrawLG(v, 1, &lg));
4058:   if (!n) PetscCall(PetscDrawLGReset(lg));
4059:   PetscCall(PetscDrawLGGetDraw(lg, &draw));
4060:   PetscCall(PetscDrawSetTitle(draw, "% elements > .2*max element"));
4061:   PetscCall(SNESMonitorRange_Private(snes, n, &per));
4062:   x = (PetscReal)n;
4063:   y = 100.0 * per;
4064:   PetscCall(PetscDrawLGAddPoint(lg, &x, &y));
4065:   if (n < 20 || !(n % 5) || snes->reason) {
4066:     PetscCall(PetscDrawLGDraw(lg));
4067:     PetscCall(PetscDrawLGSave(lg));
4068:   }
4070:   PetscCall(PetscViewerDrawGetDrawLG(v, 2, &lg));
4071:   if (!n) {
4072:     prev = rnorm;
4073:     PetscCall(PetscDrawLGReset(lg));
4074:   }
4075:   PetscCall(PetscDrawLGGetDraw(lg, &draw));
4076:   PetscCall(PetscDrawSetTitle(draw, "(norm -oldnorm)/oldnorm"));
4077:   x = (PetscReal)n;
4078:   y = (prev - rnorm) / prev;
4079:   PetscCall(PetscDrawLGAddPoint(lg, &x, &y));
4080:   if (n < 20 || !(n % 5) || snes->reason) {
4081:     PetscCall(PetscDrawLGDraw(lg));
4082:     PetscCall(PetscDrawLGSave(lg));
4083:   }
4085:   PetscCall(PetscViewerDrawGetDrawLG(v, 3, &lg));
4086:   if (!n) PetscCall(PetscDrawLGReset(lg));
4087:   PetscCall(PetscDrawLGGetDraw(lg, &draw));
4088:   PetscCall(PetscDrawSetTitle(draw, "(norm -oldnorm)/oldnorm*(% > .2 max)"));
4089:   x = (PetscReal)n;
4090:   y = (prev - rnorm) / (prev * per);
4091:   if (n > 2) { /*skip initial crazy value */
4092:     PetscCall(PetscDrawLGAddPoint(lg, &x, &y));
4093:   }
4094:   if (n < 20 || !(n % 5) || snes->reason) {
4095:     PetscCall(PetscDrawLGDraw(lg));
4096:     PetscCall(PetscDrawLGSave(lg));
4097:   }
4098:   prev = rnorm;
4099:   PetscFunctionReturn(PETSC_SUCCESS);
4100: }
4102: /*@
4103:   SNESConverged - Run the convergence test and update the `SNESConvergedReason`.
4105:   Collective
4107:   Input Parameters:
4108: + snes  - the `SNES` context
4109: . it    - current iteration
4110: . xnorm - 2-norm of current iterate
4111: . snorm - 2-norm of current step
4112: - fnorm - 2-norm of function
4114:   Level: developer
4116:   Note:
4117:   This routine is called by the `SNESSolve()` implementations.
4118:   It does not typically need to be called by the user.
4120: .seealso: [](ch_snes), `SNES`, `SNESSolve`, `SNESSetConvergenceTest()`, `SNESGetConvergenceTest()`
4121: @*/
4122: PetscErrorCode SNESConverged(SNES snes, PetscInt it, PetscReal xnorm, PetscReal snorm, PetscReal fnorm)
4123: {
4124:   PetscFunctionBegin;
4125:   if (!snes->reason) {
4126:     if (snes->normschedule == SNES_NORM_ALWAYS) PetscUseTypeMethod(snes, converged, it, xnorm, snorm, fnorm, &snes->reason, snes->cnvP);
4127:     if (it == snes->max_its && !snes->reason) {
4128:       if (snes->normschedule == SNES_NORM_ALWAYS) {
4129:         PetscCall(PetscInfo(snes, "Maximum number of iterations has been reached: %" PetscInt_FMT "\n", snes->max_its));
4130:         snes->reason = SNES_DIVERGED_MAX_IT;
4131:       } else snes->reason = SNES_CONVERGED_ITS;
4132:     }
4133:   }
4134:   PetscFunctionReturn(PETSC_SUCCESS);
4135: }
4137: /*@
4138:   SNESMonitor - runs any `SNES` monitor routines provided with `SNESMonitor()` or the options database
4140:   Collective
4142:   Input Parameters:
4143: + snes  - nonlinear solver context obtained from `SNESCreate()`
4144: . iter  - current iteration number
4145: - rnorm - current relative norm of the residual
4147:   Level: developer
4149:   Note:
4150:   This routine is called by the `SNESSolve()` implementations.
4151:   It does not typically need to be called by the user.
4153: .seealso: [](ch_snes), `SNES`, `SNESMonitorSet()`
4154: @*/
4155: PetscErrorCode SNESMonitor(SNES snes, PetscInt iter, PetscReal rnorm)
4156: {
4157:   PetscInt i, n = snes->numbermonitors;
4159:   PetscFunctionBegin;
4160:   if (n > 0) SNESCheckFunctionNorm(snes, rnorm);
4161:   PetscCall(VecLockReadPush(snes->vec_sol));
4162:   for (i = 0; i < n; i++) PetscCall((*snes->monitor[i])(snes, iter, rnorm, snes->monitorcontext[i]));
4163:   PetscCall(VecLockReadPop(snes->vec_sol));
4164:   PetscFunctionReturn(PETSC_SUCCESS);
4165: }
4167: /* ------------ Routines to set performance monitoring options ----------- */
4169: /*MC
4170:     SNESMonitorFunction - functional form passed to `SNESMonitorSet()` to monitor convergence of nonlinear solver
4172:      Synopsis:
4173: #include <petscsnes.h>
4174:     PetscErrorCode SNESMonitorFunction(SNES snes, PetscInt its, PetscReal norm, void *mctx)
4176:      Collective
4178:     Input Parameters:
4179: +    snes - the `SNES` context
4180: .    its - iteration number
4181: .    norm - 2-norm function value (may be estimated)
4182: -    mctx - [optional] monitoring context
4184:    Level: advanced
4186: .seealso: [](ch_snes), `SNESMonitorSet()`, `SNESMonitorSet()`, `SNESMonitorGet()`
4187: M*/
4189: /*@C
4190:   SNESMonitorSet - Sets an ADDITIONAL function that is to be used at every
4191:   iteration of the `SNES` nonlinear solver to display the iteration's
4192:   progress.
4194:   Logically Collective
4196:   Input Parameters:
4197: + snes           - the `SNES` context
4198: . f              - the monitor function,  for the calling sequence see `SNESMonitorFunction`
4199: . mctx           - [optional] user-defined context for private data for the monitor routine (use `NULL` if no context is desired)
4200: - monitordestroy - [optional] routine that frees monitor context (may be `NULL`)
4202:   Options Database Keys:
4203: + -snes_monitor               - sets `SNESMonitorDefault()`
4204: . -snes_monitor draw::draw_lg - sets line graph monitor,
4205: - -snes_monitor_cancel        - cancels all monitors that have been hardwired into a code by calls to `SNESMonitorSet()`, but does not cancel those set via
4206:                                 the options database.
4208:   Level: intermediate
4210:   Note:
4211:   Several different monitoring routines may be set by calling
4212:   `SNESMonitorSet()` multiple times; all will be called in the
4213:   order in which they were set.
4215:   Fortran Note:
4216:   Only a single monitor function can be set for each `SNES` object
4218: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESMonitorDefault()`, `SNESMonitorCancel()`, `SNESMonitorFunction`
4219: @*/
4220: PetscErrorCode SNESMonitorSet(SNES snes, PetscErrorCode (*f)(SNES, PetscInt, PetscReal, void *), void *mctx, PetscErrorCode (*monitordestroy)(void **))
4221: {
4222:   PetscInt  i;
4223:   PetscBool identical;
4225:   PetscFunctionBegin;
4227:   for (i = 0; i < snes->numbermonitors; i++) {
4228:     PetscCall(PetscMonitorCompare((PetscErrorCode (*)(void))f, mctx, monitordestroy, (PetscErrorCode (*)(void))snes->monitor[i], snes->monitorcontext[i], snes->monitordestroy[i], &identical));
4229:     if (identical) PetscFunctionReturn(PETSC_SUCCESS);
4230:   }
4231:   PetscCheck(snes->numbermonitors < MAXSNESMONITORS, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Too many monitors set");
4232:   snes->monitor[snes->numbermonitors]          = f;
4233:   snes->monitordestroy[snes->numbermonitors]   = monitordestroy;
4234:   snes->monitorcontext[snes->numbermonitors++] = (void *)mctx;
4235:   PetscFunctionReturn(PETSC_SUCCESS);
4236: }
4238: /*@
4239:   SNESMonitorCancel - Clears all the monitor functions for a `SNES` object.
4241:   Logically Collective
4243:   Input Parameter:
4244: . snes - the `SNES` context
4246:   Options Database Key:
4247: . -snes_monitor_cancel - cancels all monitors that have been hardwired
4248:                          into a code by calls to `SNESMonitorSet()`, but does not cancel those
4249:                          set via the options database
4251:   Level: intermediate
4253:   Note:
4254:   There is no way to clear one specific monitor from a `SNES` object.
4256: .seealso: [](ch_snes), `SNES`, `SNESMonitorGet()`, `SNESMonitorDefault()`, `SNESMonitorSet()`
4257: @*/
4258: PetscErrorCode SNESMonitorCancel(SNES snes)
4259: {
4260:   PetscInt i;
4262:   PetscFunctionBegin;
4264:   for (i = 0; i < snes->numbermonitors; i++) {
4265:     if (snes->monitordestroy[i]) PetscCall((*snes->monitordestroy[i])(&snes->monitorcontext[i]));
4266:   }
4267:   snes->numbermonitors = 0;
4268:   PetscFunctionReturn(PETSC_SUCCESS);
4269: }
4271: /*MC
4272:     SNESConvergenceTestFunction - functional form used for testing of convergence of nonlinear solver
4274:      Synopsis:
4275: #include <petscsnes.h>
4276:      PetscErrorCode SNESConvergenceTest(SNES snes, PetscInt it, PetscReal xnorm, PetscReal gnorm, PetscReal f, SNESConvergedReason *reason, void *cctx)
4278:      Collective
4280:     Input Parameters:
4281: +    snes - the `SNES` context
4282: .    it - current iteration (0 is the first and is before any Newton step)
4283: .    xnorm - 2-norm of current iterate
4284: .    gnorm - 2-norm of current step
4285: .    f - 2-norm of function
4286: -    cctx - [optional] convergence context
4288:     Output Parameter:
4289: .    reason - reason for convergence/divergence, only needs to be set when convergence or divergence is detected
4291:    Level: intermediate
4293: .seealso: [](ch_snes), `SNES`, `SNESSolve`, `SNESSetConvergenceTest()`, `SNESGetConvergenceTest()`
4294: M*/
4296: /*@C
4297:   SNESSetConvergenceTest - Sets the function that is to be used
4298:   to test for convergence of the nonlinear iterative solution.
4300:   Logically Collective
4302:   Input Parameters:
4303: + snes                        - the `SNES` context
4304: . SNESConvergenceTestFunction - routine to test for convergence
4305: . cctx                        - [optional] context for private data for the convergence routine  (may be `NULL`)
4306: - destroy                     - [optional] destructor for the context (may be `NULL`; `PETSC_NULL_FUNCTION` in Fortran)
4308:   Level: advanced
4310: .seealso: [](ch_snes), `SNES`, `SNESConvergedDefault()`, `SNESConvergedSkip()`, `SNESConvergenceTestFunction`
4311: @*/
4312: PetscErrorCode SNESSetConvergenceTest(SNES snes, PetscErrorCode (*SNESConvergenceTestFunction)(SNES, PetscInt, PetscReal, PetscReal, PetscReal, SNESConvergedReason *, void *), void *cctx, PetscErrorCode (*destroy)(void *))
4313: {
4314:   PetscFunctionBegin;
4316:   if (!SNESConvergenceTestFunction) SNESConvergenceTestFunction = SNESConvergedSkip;
4317:   if (snes->ops->convergeddestroy) PetscCall((*snes->ops->convergeddestroy)(snes->cnvP));
4318:   snes->ops->converged        = SNESConvergenceTestFunction;
4319:   snes->ops->convergeddestroy = destroy;
4320:   snes->cnvP                  = cctx;
4321:   PetscFunctionReturn(PETSC_SUCCESS);
4322: }
4324: /*@
4325:   SNESGetConvergedReason - Gets the reason the `SNES` iteration was stopped, which may be due to convergence, divergence, or stagnation
4327:   Not Collective
4329:   Input Parameter:
4330: . snes - the `SNES` context
4332:   Output Parameter:
4333: . reason - negative value indicates diverged, positive value converged, see `SNESConvergedReason` for the individual convergence tests for complete lists
4335:   Options Database Key:
4336: . -snes_converged_reason - prints the reason to standard out
4338:   Level: intermediate
4340:   Note:
4341:   Should only be called after the call the `SNESSolve()` is complete, if it is called earlier it returns the value `SNES__CONVERGED_ITERATING`.
4343: .seealso: [](ch_snes), `SNESSolve()`, `SNESSetConvergenceTest()`, `SNESSetConvergedReason()`, `SNESConvergedReason`, `SNESGetConvergedReasonString()`
4344: @*/
4345: PetscErrorCode SNESGetConvergedReason(SNES snes, SNESConvergedReason *reason)
4346: {
4347:   PetscFunctionBegin;
4349:   PetscAssertPointer(reason, 2);
4350:   *reason = snes->reason;
4351:   PetscFunctionReturn(PETSC_SUCCESS);
4352: }
4354: /*@C
4355:   SNESGetConvergedReasonString - Return a human readable string for `SNESConvergedReason`
4357:   Not Collective
4359:   Input Parameter:
4360: . snes - the `SNES` context
4362:   Output Parameter:
4363: . strreason - a human readable string that describes `SNES` converged reason
4365:   Level: beginner
4367: .seealso: [](ch_snes), `SNES`, `SNESGetConvergedReason()`
4368: @*/
4369: PetscErrorCode SNESGetConvergedReasonString(SNES snes, const char **strreason)
4370: {
4371:   PetscFunctionBegin;
4373:   PetscAssertPointer(strreason, 2);
4374:   *strreason = SNESConvergedReasons[snes->reason];
4375:   PetscFunctionReturn(PETSC_SUCCESS);
4376: }
4378: /*@
4379:   SNESSetConvergedReason - Sets the reason the `SNES` iteration was stopped.
4381:   Not Collective
4383:   Input Parameters:
4384: + snes   - the `SNES` context
4385: - reason - negative value indicates diverged, positive value converged, see `SNESConvergedReason` or the
4386:             manual pages for the individual convergence tests for complete lists
4388:   Level: developer
4390:   Developer Note:
4391:   Called inside the various `SNESSolve()` implementations
4393: .seealso: [](ch_snes), `SNESGetConvergedReason()`, `SNESSetConvergenceTest()`, `SNESConvergedReason`
4394: @*/
4395: PetscErrorCode SNESSetConvergedReason(SNES snes, SNESConvergedReason reason)
4396: {
4397:   PetscFunctionBegin;
4399:   PetscCheck(!snes->errorifnotconverged || reason > 0, PetscObjectComm((PetscObject)snes), PETSC_ERR_PLIB, "SNES code should have previously errored due to negative reason");
4400:   snes->reason = reason;
4401:   PetscFunctionReturn(PETSC_SUCCESS);
4402: }
4404: /*@
4405:   SNESSetConvergenceHistory - Sets the arrays used to hold the convergence history.
4407:   Logically Collective
4409:   Input Parameters:
4410: + snes  - iterative context obtained from `SNESCreate()`
4411: . a     - array to hold history, this array will contain the function norms computed at each step
4412: . its   - integer array holds the number of linear iterations for each solve.
4413: . na    - size of `a` and `its`
4414: - reset - `PETSC_TRUE` indicates each new nonlinear solve resets the history counter to zero,
4415:           else it continues storing new values for new nonlinear solves after the old ones
4417:   Level: intermediate
4419:   Notes:
4420:   If 'a' and 'its' are `NULL` then space is allocated for the history. If 'na' is `PETSC_DECIDE` then a
4421:   default array of length 1,000 is allocated.
4423:   This routine is useful, e.g., when running a code for purposes
4424:   of accurate performance monitoring, when no I/O should be done
4425:   during the section of code that is being timed.
4427:   If the arrays run out of space after a number of iterations then the later values are not saved in the history
4429: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergenceHistory()`
4430: @*/
4431: PetscErrorCode SNESSetConvergenceHistory(SNES snes, PetscReal a[], PetscInt its[], PetscInt na, PetscBool reset)
4432: {
4433:   PetscFunctionBegin;
4435:   if (a) PetscAssertPointer(a, 2);
4436:   if (its) PetscAssertPointer(its, 3);
4437:   if (!a) {
4438:     if (na == PETSC_DECIDE) na = 1000;
4439:     PetscCall(PetscCalloc2(na, &a, na, &its));
4440:     snes->conv_hist_alloc = PETSC_TRUE;
4441:   }
4442:   snes->conv_hist       = a;
4443:   snes->conv_hist_its   = its;
4444:   snes->conv_hist_max   = (size_t)na;
4445:   snes->conv_hist_len   = 0;
4446:   snes->conv_hist_reset = reset;
4447:   PetscFunctionReturn(PETSC_SUCCESS);
4448: }
4450: #if defined(PETSC_HAVE_MATLAB)
4451:   #include <engine.h> /* MATLAB include file */
4452:   #include <mex.h>    /* MATLAB include file */
4454: PETSC_EXTERN mxArray *SNESGetConvergenceHistoryMatlab(SNES snes)
4455: {
4456:   mxArray   *mat;
4457:   PetscInt   i;
4458:   PetscReal *ar;
4460:   mat = mxCreateDoubleMatrix(snes->conv_hist_len, 1, mxREAL);
4461:   ar  = (PetscReal *)mxGetData(mat);
4462:   for (i = 0; i < snes->conv_hist_len; i++) ar[i] = snes->conv_hist[i];
4463:   return mat;
4464: }
4465: #endif
4467: /*@C
4468:   SNESGetConvergenceHistory - Gets the arrays used to hold the convergence history.
4470:   Not Collective
4472:   Input Parameter:
4473: . snes - iterative context obtained from `SNESCreate()`
4475:   Output Parameters:
4476: + a   - array to hold history, usually was set with `SNESSetConvergenceHistory()`
4477: . its - integer array holds the number of linear iterations (or
4478:          negative if not converged) for each solve.
4479: - na  - size of `a` and `its`
4481:   Level: intermediate
4483:   Note:
4484:   This routine is useful, e.g., when running a code for purposes
4485:   of accurate performance monitoring, when no I/O should be done
4486:   during the section of code that is being timed.
4488:   Fortran Note:
4489:   The calling sequence for this routine in Fortran is
4490: .vb
4491:     call SNESGetConvergenceHistory(SNES snes, integer na, integer ierr)
4492: .ve
4494: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESSetConvergenceHistory()`
4495: @*/
4496: PetscErrorCode SNESGetConvergenceHistory(SNES snes, PetscReal *a[], PetscInt *its[], PetscInt *na)
4497: {
4498:   PetscFunctionBegin;
4500:   if (a) *a = snes->conv_hist;
4501:   if (its) *its = snes->conv_hist_its;
4502:   if (na) *na = (PetscInt)snes->conv_hist_len;
4503:   PetscFunctionReturn(PETSC_SUCCESS);
4504: }
4506: /*@C
4507:   SNESSetUpdate - Sets the general-purpose update function called
4508:   at the beginning of every iteration of the nonlinear solve. Specifically
4509:   it is called just before the Jacobian is "evaluated" and after the function
4510:   evaluation.
4512:   Logically Collective
4514:   Input Parameters:
4515: + snes - The nonlinear solver context
4516: - func - The update function; for calling sequence see `SNESUpdateFn`
4518:   Level: advanced
4520:   Notes:
4521:   This is NOT what one uses to update the ghost points before a function evaluation, that should be done at the beginning of your function provided
4522:   to `SNESSetFunction()`, or `SNESSetPicard()`
4523:   This is not used by most users, and it is intended to provide a general hook that is run
4524:   right before the direction step is computed.
4525:   Users are free to modify the current residual vector,
4526:   the current linearization point, or any other vector associated to the specific solver used.
4527:   If such modifications take place, it is the user responsibility to update all the relevant
4528:   vectors.
4530:   There are a variety of function hooks one many set that are called at different stages of the nonlinear solution process, see the functions listed below.
4532: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESSetJacobian()`, `SNESLineSearchSetPreCheck()`, `SNESLineSearchSetPostCheck()`, `SNESNewtonTRSetPreCheck()`, `SNESNewtonTRSetPostCheck()`,
4533:          `SNESMonitorSet()`
4534: @*/
4535: PetscErrorCode SNESSetUpdate(SNES snes, SNESUpdateFn *func)
4536: {
4537:   PetscFunctionBegin;
4539:   snes->ops->update = func;
4540:   PetscFunctionReturn(PETSC_SUCCESS);
4541: }
4543: /*@
4544:   SNESConvergedReasonView - Displays the reason a `SNES` solve converged or diverged to a viewer
4546:   Collective
4548:   Input Parameters:
4549: + snes   - iterative context obtained from `SNESCreate()`
4550: - viewer - the viewer to display the reason
4552:   Options Database Keys:
4553: + -snes_converged_reason          - print reason for converged or diverged, also prints number of iterations
4554: - -snes_converged_reason ::failed - only print reason and number of iterations when diverged
4556:   Level: beginner
4558:   Note:
4559:   To change the format of the output call `PetscViewerPushFormat`(viewer,format) before this call. Use `PETSC_VIEWER_DEFAULT` for the default,
4560:   use `PETSC_VIEWER_FAILED` to only display a reason if it fails.
4562: .seealso: [](ch_snes), `SNESConvergedReason`, `PetscViewer`, `SNES`,
4563:           `SNESCreate()`, `SNESSetUp()`, `SNESDestroy()`, `SNESSetTolerances()`, `SNESConvergedDefault()`, `SNESGetConvergedReason()`,
4564:           `SNESConvergedReasonViewFromOptions()`,
4565:           `PetscViewerPushFormat()`, `PetscViewerPopFormat()`
4566: @*/
4567: PetscErrorCode SNESConvergedReasonView(SNES snes, PetscViewer viewer)
4568: {
4569:   PetscViewerFormat format;
4570:   PetscBool         isAscii;
4572:   PetscFunctionBegin;
4573:   if (!viewer) viewer = PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes));
4574:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &isAscii));
4575:   if (isAscii) {
4576:     PetscCall(PetscViewerGetFormat(viewer, &format));
4577:     PetscCall(PetscViewerASCIIAddTab(viewer, ((PetscObject)snes)->tablevel + 1));
4578:     if (format == PETSC_VIEWER_ASCII_INFO_DETAIL) {
4579:       DM       dm;
4580:       Vec      u;
4581:       PetscDS  prob;
4582:       PetscInt Nf, f;
4583:       PetscErrorCode (**exactSol)(PetscInt, PetscReal, const PetscReal[], PetscInt, PetscScalar[], void *);
4584:       void    **exactCtx;
4585:       PetscReal error;
4587:       PetscCall(SNESGetDM(snes, &dm));
4588:       PetscCall(SNESGetSolution(snes, &u));
4589:       PetscCall(DMGetDS(dm, &prob));
4590:       PetscCall(PetscDSGetNumFields(prob, &Nf));
4591:       PetscCall(PetscMalloc2(Nf, &exactSol, Nf, &exactCtx));
4592:       for (f = 0; f < Nf; ++f) PetscCall(PetscDSGetExactSolution(prob, f, &exactSol[f], &exactCtx[f]));
4593:       PetscCall(DMComputeL2Diff(dm, 0.0, exactSol, exactCtx, u, &error));
4594:       PetscCall(PetscFree2(exactSol, exactCtx));
4595:       if (error < 1.0e-11) PetscCall(PetscViewerASCIIPrintf(viewer, "L_2 Error: < 1.0e-11\n"));
4596:       else PetscCall(PetscViewerASCIIPrintf(viewer, "L_2 Error: %g\n", (double)error));
4597:     }
4598:     if (snes->reason > 0 && format != PETSC_VIEWER_FAILED) {
4599:       if (((PetscObject)snes)->prefix) {
4600:         PetscCall(PetscViewerASCIIPrintf(viewer, "Nonlinear %s solve converged due to %s iterations %" PetscInt_FMT "\n", ((PetscObject)snes)->prefix, SNESConvergedReasons[snes->reason], snes->iter));
4601:       } else {
4602:         PetscCall(PetscViewerASCIIPrintf(viewer, "Nonlinear solve converged due to %s iterations %" PetscInt_FMT "\n", SNESConvergedReasons[snes->reason], snes->iter));
4603:       }
4604:     } else if (snes->reason <= 0) {
4605:       if (((PetscObject)snes)->prefix) {
4606:         PetscCall(PetscViewerASCIIPrintf(viewer, "Nonlinear %s solve did not converge due to %s iterations %" PetscInt_FMT "\n", ((PetscObject)snes)->prefix, SNESConvergedReasons[snes->reason], snes->iter));
4607:       } else {
4608:         PetscCall(PetscViewerASCIIPrintf(viewer, "Nonlinear solve did not converge due to %s iterations %" PetscInt_FMT "\n", SNESConvergedReasons[snes->reason], snes->iter));
4609:       }
4610:     }
4611:     PetscCall(PetscViewerASCIISubtractTab(viewer, ((PetscObject)snes)->tablevel + 1));
4612:   }
4613:   PetscFunctionReturn(PETSC_SUCCESS);
4614: }
4616: /*@C
4617:   SNESConvergedReasonViewSet - Sets an ADDITIONAL function that is to be used at the
4618:   end of the nonlinear solver to display the convergence reason of the nonlinear solver.
4620:   Logically Collective
4622:   Input Parameters:
4623: + snes              - the `SNES` context
4624: . f                 - the `SNESConvergedReason` view function
4625: . vctx              - [optional] user-defined context for private data for the `SNESConvergedReason` view function (use `NULL` if no context is desired)
4626: - reasonviewdestroy - [optional] routine that frees the context (may be `NULL`)
4628:   Calling sequence of `f`:
4629: + snes - the `SNES` context
4630: - vctx - [optional] user-defined context for private data for the function
4632:   Calling sequence of `reasonviewerdestroy`:
4633: . vctx - [optional] user-defined context for private data for the function
4635:   Options Database Keys:
4636: + -snes_converged_reason             - sets a default `SNESConvergedReasonView()`
4637: - -snes_converged_reason_view_cancel - cancels all converged reason viewers that have been hardwired into a code by
4638:                                        calls to `SNESConvergedReasonViewSet()`, but does not cancel those set via the options database.
4640:   Level: intermediate
4642:   Note:
4643:   Several different converged reason view routines may be set by calling
4644:   `SNESConvergedReasonViewSet()` multiple times; all will be called in the
4645:   order in which they were set.
4647: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESConvergedReason`, `SNESGetConvergedReason()`, `SNESConvergedReasonView()`, `SNESConvergedReasonViewCancel()`
4648: @*/
4649: PetscErrorCode SNESConvergedReasonViewSet(SNES snes, PetscErrorCode (*f)(SNES snes, void *vctx), void *vctx, PetscErrorCode (*reasonviewdestroy)(void **vctx))
4650: {
4651:   PetscInt  i;
4652:   PetscBool identical;
4654:   PetscFunctionBegin;
4656:   for (i = 0; i < snes->numberreasonviews; i++) {
4657:     PetscCall(PetscMonitorCompare((PetscErrorCode (*)(void))f, vctx, reasonviewdestroy, (PetscErrorCode (*)(void))snes->reasonview[i], snes->reasonviewcontext[i], snes->reasonviewdestroy[i], &identical));
4658:     if (identical) PetscFunctionReturn(PETSC_SUCCESS);
4659:   }
4660:   PetscCheck(snes->numberreasonviews < MAXSNESREASONVIEWS, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Too many SNES reasonview set");
4661:   snes->reasonview[snes->numberreasonviews]          = f;
4662:   snes->reasonviewdestroy[snes->numberreasonviews]   = reasonviewdestroy;
4663:   snes->reasonviewcontext[snes->numberreasonviews++] = (void *)vctx;
4664:   PetscFunctionReturn(PETSC_SUCCESS);
4665: }
4667: /*@
4668:   SNESConvergedReasonViewFromOptions - Processes command line options to determine if/how a `SNESConvergedReason` is to be viewed at the end of `SNESSolve()`
4669:   All the user-provided viewer routines set with `SNESConvergedReasonViewSet()` will be called, if they exist.
4671:   Collective
4673:   Input Parameter:
4674: . snes - the `SNES` object
4676:   Level: advanced
4678: .seealso: [](ch_snes), `SNES`, `SNESConvergedReason`, `SNESConvergedReasonViewSet()`, `SNESCreate()`, `SNESSetUp()`, `SNESDestroy()`,
4679:           `SNESSetTolerances()`, `SNESConvergedDefault()`, `SNESGetConvergedReason()`, `SNESConvergedReasonView()`
4680: @*/
4681: PetscErrorCode SNESConvergedReasonViewFromOptions(SNES snes)
4682: {
4683:   static PetscBool incall = PETSC_FALSE;
4685:   PetscFunctionBegin;
4686:   if (incall) PetscFunctionReturn(PETSC_SUCCESS);
4687:   incall = PETSC_TRUE;
4689:   /* All user-provided viewers are called first, if they exist. */
4690:   for (PetscInt i = 0; i < snes->numberreasonviews; i++) PetscCall((*snes->reasonview[i])(snes, snes->reasonviewcontext[i]));
4692:   /* Call PETSc default routine if users ask for it */
4693:   if (snes->convergedreasonviewer) {
4694:     PetscCall(PetscViewerPushFormat(snes->convergedreasonviewer, snes->convergedreasonformat));
4695:     PetscCall(SNESConvergedReasonView(snes, snes->convergedreasonviewer));
4696:     PetscCall(PetscViewerPopFormat(snes->convergedreasonviewer));
4697:   }
4698:   incall = PETSC_FALSE;
4699:   PetscFunctionReturn(PETSC_SUCCESS);
4700: }
4702: /*@
4703:   SNESSolve - Solves a nonlinear system $F(x) = b $ associated with a `SNES` object
4705:   Collective
4707:   Input Parameters:
4708: + snes - the `SNES` context
4709: . b    - the constant part of the equation $F(x) = b$, or `NULL` to use zero.
4710: - x    - the solution vector.
4712:   Level: beginner
4714:   Note:
4715:   The user should initialize the vector, `x`, with the initial guess
4716:   for the nonlinear solve prior to calling `SNESSolve()` .
4718: .seealso: [](ch_snes), `SNES`, `SNESCreate()`, `SNESDestroy()`, `SNESSetFunction()`, `SNESSetJacobian()`, `SNESSetGridSequence()`, `SNESGetSolution()`,
4719:           `SNESNewtonTRSetPreCheck()`, `SNESNewtonTRGetPreCheck()`, `SNESNewtonTRSetPostCheck()`, `SNESNewtonTRGetPostCheck()`,
4720:           `SNESLineSearchSetPostCheck()`, `SNESLineSearchGetPostCheck()`, `SNESLineSearchSetPreCheck()`, `SNESLineSearchGetPreCheck()`
4721: @*/
4722: PetscErrorCode SNESSolve(SNES snes, Vec b, Vec x)
4723: {
4724:   PetscBool flg;
4725:   PetscInt  grid;
4726:   Vec       xcreated = NULL;
4727:   DM        dm;
4729:   PetscFunctionBegin;
4732:   if (x) PetscCheckSameComm(snes, 1, x, 3);
4734:   if (b) PetscCheckSameComm(snes, 1, b, 2);
4736:   /* High level operations using the nonlinear solver */
4737:   {
4738:     PetscViewer       viewer;
4739:     PetscViewerFormat format;
4740:     PetscInt          num;
4741:     PetscBool         flg;
4742:     static PetscBool  incall = PETSC_FALSE;
4744:     if (!incall) {
4745:       /* Estimate the convergence rate of the discretization */
4746:       PetscCall(PetscOptionsCreateViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_convergence_estimate", &viewer, &format, &flg));
4747:       if (flg) {
4748:         PetscConvEst conv;
4749:         DM           dm;
4750:         PetscReal   *alpha; /* Convergence rate of the solution error for each field in the L_2 norm */
4751:         PetscInt     Nf;
4753:         incall = PETSC_TRUE;
4754:         PetscCall(SNESGetDM(snes, &dm));
4755:         PetscCall(DMGetNumFields(dm, &Nf));
4756:         PetscCall(PetscCalloc1(Nf, &alpha));
4757:         PetscCall(PetscConvEstCreate(PetscObjectComm((PetscObject)snes), &conv));
4758:         PetscCall(PetscConvEstSetSolver(conv, (PetscObject)snes));
4759:         PetscCall(PetscConvEstSetFromOptions(conv));
4760:         PetscCall(PetscConvEstSetUp(conv));
4761:         PetscCall(PetscConvEstGetConvRate(conv, alpha));
4762:         PetscCall(PetscViewerPushFormat(viewer, format));
4763:         PetscCall(PetscConvEstRateView(conv, alpha, viewer));
4764:         PetscCall(PetscViewerPopFormat(viewer));
4765:         PetscCall(PetscViewerDestroy(&viewer));
4766:         PetscCall(PetscConvEstDestroy(&conv));
4767:         PetscCall(PetscFree(alpha));
4768:         incall = PETSC_FALSE;
4769:       }
4770:       /* Adaptively refine the initial grid */
4771:       num = 1;
4772:       PetscCall(PetscOptionsGetInt(NULL, ((PetscObject)snes)->prefix, "-snes_adapt_initial", &num, &flg));
4773:       if (flg) {
4774:         DMAdaptor adaptor;
4776:         incall = PETSC_TRUE;
4777:         PetscCall(DMAdaptorCreate(PetscObjectComm((PetscObject)snes), &adaptor));
4778:         PetscCall(DMAdaptorSetSolver(adaptor, snes));
4779:         PetscCall(DMAdaptorSetSequenceLength(adaptor, num));
4780:         PetscCall(DMAdaptorSetFromOptions(adaptor));
4781:         PetscCall(DMAdaptorSetUp(adaptor));
4782:         PetscCall(DMAdaptorAdapt(adaptor, x, DM_ADAPTATION_INITIAL, &dm, &x));
4783:         PetscCall(DMAdaptorDestroy(&adaptor));
4784:         incall = PETSC_FALSE;
4785:       }
4786:       /* Use grid sequencing to adapt */
4787:       num = 0;
4788:       PetscCall(PetscOptionsGetInt(NULL, ((PetscObject)snes)->prefix, "-snes_adapt_sequence", &num, NULL));
4789:       if (num) {
4790:         DMAdaptor   adaptor;
4791:         const char *prefix;
4793:         incall = PETSC_TRUE;
4794:         PetscCall(DMAdaptorCreate(PetscObjectComm((PetscObject)snes), &adaptor));
4795:         PetscCall(SNESGetOptionsPrefix(snes, &prefix));
4796:         PetscCall(DMAdaptorSetOptionsPrefix(adaptor, prefix));
4797:         PetscCall(DMAdaptorSetSolver(adaptor, snes));
4798:         PetscCall(DMAdaptorSetSequenceLength(adaptor, num));
4799:         PetscCall(DMAdaptorSetFromOptions(adaptor));
4800:         PetscCall(DMAdaptorSetUp(adaptor));
4801:         PetscCall(PetscObjectViewFromOptions((PetscObject)adaptor, NULL, "-snes_adapt_view"));
4802:         PetscCall(DMAdaptorAdapt(adaptor, x, DM_ADAPTATION_SEQUENTIAL, &dm, &x));
4803:         PetscCall(DMAdaptorDestroy(&adaptor));
4804:         incall = PETSC_FALSE;
4805:       }
4806:     }
4807:   }
4808:   if (!x) x = snes->vec_sol;
4809:   if (!x) {
4810:     PetscCall(SNESGetDM(snes, &dm));
4811:     PetscCall(DMCreateGlobalVector(dm, &xcreated));
4812:     x = xcreated;
4813:   }
4814:   PetscCall(SNESViewFromOptions(snes, NULL, "-snes_view_pre"));
4816:   for (grid = 0; grid < snes->gridsequence; grid++) PetscCall(PetscViewerASCIIPushTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes))));
4817:   for (grid = 0; grid < snes->gridsequence + 1; grid++) {
4818:     /* set solution vector */
4819:     if (!grid) PetscCall(PetscObjectReference((PetscObject)x));
4820:     PetscCall(VecDestroy(&snes->vec_sol));
4821:     snes->vec_sol = x;
4822:     PetscCall(SNESGetDM(snes, &dm));
4824:     /* set affine vector if provided */
4825:     if (b) PetscCall(PetscObjectReference((PetscObject)b));
4826:     PetscCall(VecDestroy(&snes->vec_rhs));
4827:     snes->vec_rhs = b;
4829:     if (snes->vec_rhs) PetscCheck(snes->vec_func != snes->vec_rhs, PETSC_COMM_SELF, PETSC_ERR_ARG_IDN, "Right hand side vector cannot be function vector");
4830:     PetscCheck(snes->vec_func != snes->vec_sol, PETSC_COMM_SELF, PETSC_ERR_ARG_IDN, "Solution vector cannot be function vector");
4831:     PetscCheck(snes->vec_rhs != snes->vec_sol, PETSC_COMM_SELF, PETSC_ERR_ARG_IDN, "Solution vector cannot be right-hand side vector");
4832:     if (!snes->vec_sol_update /* && snes->vec_sol */) PetscCall(VecDuplicate(snes->vec_sol, &snes->vec_sol_update));
4833:     PetscCall(DMShellSetGlobalVector(dm, snes->vec_sol));
4834:     PetscCall(SNESSetUp(snes));
4836:     if (!grid) {
4837:       if (snes->ops->computeinitialguess) PetscCallBack("SNES callback compute initial guess", (*snes->ops->computeinitialguess)(snes, snes->vec_sol, snes->initialguessP));
4838:     }
4840:     if (snes->conv_hist_reset) snes->conv_hist_len = 0;
4841:     PetscCall(SNESResetCounters(snes));
4842:     snes->reason = SNES_CONVERGED_ITERATING;
4843:     PetscCall(PetscLogEventBegin(SNES_Solve, snes, 0, 0, 0));
4844:     PetscUseTypeMethod(snes, solve);
4845:     PetscCall(PetscLogEventEnd(SNES_Solve, snes, 0, 0, 0));
4846:     PetscCheck(snes->reason, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Internal error, solver %s returned without setting converged reason", ((PetscObject)snes)->type_name);
4847:     snes->domainerror = PETSC_FALSE; /* clear the flag if it has been set */
4849:     if (snes->lagjac_persist) snes->jac_iter += snes->iter;
4850:     if (snes->lagpre_persist) snes->pre_iter += snes->iter;
4852:     PetscCall(PetscOptionsCreateViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_test_local_min", NULL, NULL, &flg));
4853:     if (flg && !PetscPreLoadingOn) PetscCall(SNESTestLocalMin(snes));
4854:     /* Call converged reason views. This may involve user-provided viewers as well */
4855:     PetscCall(SNESConvergedReasonViewFromOptions(snes));
4857:     if (snes->errorifnotconverged) PetscCheck(snes->reason >= 0, PetscObjectComm((PetscObject)snes), PETSC_ERR_NOT_CONVERGED, "SNESSolve has not converged");
4858:     if (snes->reason < 0) break;
4859:     if (grid < snes->gridsequence) {
4860:       DM  fine;
4861:       Vec xnew;
4862:       Mat interp;
4864:       PetscCall(DMRefine(snes->dm, PetscObjectComm((PetscObject)snes), &fine));
4865:       PetscCheck(fine, PetscObjectComm((PetscObject)snes), PETSC_ERR_ARG_INCOMP, "DMRefine() did not perform any refinement, cannot continue grid sequencing");
4866:       PetscCall(DMCreateInterpolation(snes->dm, fine, &interp, NULL));
4867:       PetscCall(DMCreateGlobalVector(fine, &xnew));
4868:       PetscCall(MatInterpolate(interp, x, xnew));
4869:       PetscCall(DMInterpolate(snes->dm, interp, fine));
4870:       PetscCall(MatDestroy(&interp));
4871:       x = xnew;
4873:       PetscCall(SNESReset(snes));
4874:       PetscCall(SNESSetDM(snes, fine));
4875:       PetscCall(SNESResetFromOptions(snes));
4876:       PetscCall(DMDestroy(&fine));
4877:       PetscCall(PetscViewerASCIIPopTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes))));
4878:     }
4879:   }
4880:   PetscCall(SNESViewFromOptions(snes, NULL, "-snes_view"));
4881:   PetscCall(VecViewFromOptions(snes->vec_sol, (PetscObject)snes, "-snes_view_solution"));
4882:   PetscCall(DMMonitor(snes->dm));
4883:   PetscCall(SNESMonitorPauseFinal_Internal(snes));
4885:   PetscCall(VecDestroy(&xcreated));
4886:   PetscCall(PetscObjectSAWsBlock((PetscObject)snes));
4887:   PetscFunctionReturn(PETSC_SUCCESS);
4888: }
4890: /* --------- Internal routines for SNES Package --------- */
4892: /*@
4893:   SNESSetType - Sets the algorithm/method to be used to solve the nonlinear system with the given `SNES`
4895:   Collective
4897:   Input Parameters:
4898: + snes - the `SNES` context
4899: - type - a known method
4901:   Options Database Key:
4902: . -snes_type <type> - Sets the method; use -help for a list
4903:    of available methods (for instance, newtonls or newtontr)
4905:   Level: intermediate
4907:   Notes:
4908:   See `SNESType` for available methods (for instance)
4909: +    `SNESNEWTONLS` - Newton's method with line search
4910:   (systems of nonlinear equations)
4911: -    `SNESNEWTONTR` - Newton's method with trust region
4912:   (systems of nonlinear equations)
4914:   Normally, it is best to use the `SNESSetFromOptions()` command and then
4915:   set the `SNES` solver type from the options database rather than by using
4916:   this routine.  Using the options database provides the user with
4917:   maximum flexibility in evaluating the many nonlinear solvers.
4918:   The `SNESSetType()` routine is provided for those situations where it
4919:   is necessary to set the nonlinear solver independently of the command
4920:   line or options database.  This might be the case, for example, when
4921:   the choice of solver changes during the execution of the program,
4922:   and the user's application is taking responsibility for choosing the
4923:   appropriate method.
4925:   Developer Note:
4926:   `SNESRegister()` adds a constructor for a new `SNESType` to `SNESList`, `SNESSetType()` locates
4927:   the constructor in that list and calls it to create the specific object.
4929: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESType`, `SNESCreate()`, `SNESDestroy()`, `SNESGetType()`, `SNESSetFromOptions()`
4930: @*/
4931: PetscErrorCode SNESSetType(SNES snes, SNESType type)
4932: {
4933:   PetscBool match;
4934:   PetscErrorCode (*r)(SNES);
4936:   PetscFunctionBegin;
4938:   PetscAssertPointer(type, 2);
4940:   PetscCall(PetscObjectTypeCompare((PetscObject)snes, type, &match));
4941:   if (match) PetscFunctionReturn(PETSC_SUCCESS);
4943:   PetscCall(PetscFunctionListFind(SNESList, type, &r));
4944:   PetscCheck(r, PetscObjectComm((PetscObject)snes), PETSC_ERR_ARG_UNKNOWN_TYPE, "Unable to find requested SNES type %s", type);
4945:   /* Destroy the previous private SNES context */
4946:   PetscTryTypeMethod(snes, destroy);
4947:   /* Reinitialize function pointers in SNESOps structure */
4948:   snes->ops->setup          = NULL;
4949:   snes->ops->solve          = NULL;
4950:   snes->ops->view           = NULL;
4951:   snes->ops->setfromoptions = NULL;
4952:   snes->ops->destroy        = NULL;
4954:   /* It may happen the user has customized the line search before calling SNESSetType */
4955:   if (((PetscObject)snes)->type_name) PetscCall(SNESLineSearchDestroy(&snes->linesearch));
4957:   /* Call the SNESCreate_XXX routine for this particular Nonlinear solver */
4958:   snes->setupcalled = PETSC_FALSE;
4960:   PetscCall(PetscObjectChangeTypeName((PetscObject)snes, type));
4961:   PetscCall((*r)(snes));
4962:   PetscFunctionReturn(PETSC_SUCCESS);
4963: }
4965: /*@
4966:   SNESGetType - Gets the `SNES` method type and name (as a string).
4968:   Not Collective
4970:   Input Parameter:
4971: . snes - nonlinear solver context
4973:   Output Parameter:
4974: . type - `SNES` method (a character string)
4976:   Level: intermediate
4978: .seealso: [](ch_snes), `SNESSetType()`, `SNESType`, `SNESSetFromOptions()`, `SNES`
4979: @*/
4980: PetscErrorCode SNESGetType(SNES snes, SNESType *type)
4981: {
4982:   PetscFunctionBegin;
4984:   PetscAssertPointer(type, 2);
4985:   *type = ((PetscObject)snes)->type_name;
4986:   PetscFunctionReturn(PETSC_SUCCESS);
4987: }
4989: /*@
4990:   SNESSetSolution - Sets the solution vector for use by the `SNES` routines.
4992:   Logically Collective
4994:   Input Parameters:
4995: + snes - the `SNES` context obtained from `SNESCreate()`
4996: - u    - the solution vector
4998:   Level: beginner
5000: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetSolution()`, `Vec`
5001: @*/
5002: PetscErrorCode SNESSetSolution(SNES snes, Vec u)
5003: {
5004:   DM dm;
5006:   PetscFunctionBegin;
5009:   PetscCall(PetscObjectReference((PetscObject)u));
5010:   PetscCall(VecDestroy(&snes->vec_sol));
5012:   snes->vec_sol = u;
5014:   PetscCall(SNESGetDM(snes, &dm));
5015:   PetscCall(DMShellSetGlobalVector(dm, u));
5016:   PetscFunctionReturn(PETSC_SUCCESS);
5017: }
5019: /*@
5020:   SNESGetSolution - Returns the vector where the approximate solution is
5021:   stored. This is the fine grid solution when using `SNESSetGridSequence()`.
5023:   Not Collective, but `x` is parallel if `snes` is parallel
5025:   Input Parameter:
5026: . snes - the `SNES` context
5028:   Output Parameter:
5029: . x - the solution
5031:   Level: intermediate
5033: .seealso: [](ch_snes), `SNESSetSolution()`, `SNESSolve()`, `SNES`, `SNESGetSolutionUpdate()`, `SNESGetFunction()`
5034: @*/
5035: PetscErrorCode SNESGetSolution(SNES snes, Vec *x)
5036: {
5037:   PetscFunctionBegin;
5039:   PetscAssertPointer(x, 2);
5040:   *x = snes->vec_sol;
5041:   PetscFunctionReturn(PETSC_SUCCESS);
5042: }
5044: /*@
5045:   SNESGetSolutionUpdate - Returns the vector where the solution update is
5046:   stored.
5048:   Not Collective, but `x` is parallel if `snes` is parallel
5050:   Input Parameter:
5051: . snes - the `SNES` context
5053:   Output Parameter:
5054: . x - the solution update
5056:   Level: advanced
5058: .seealso: [](ch_snes), `SNES`, `SNESGetSolution()`, `SNESGetFunction()`
5059: @*/
5060: PetscErrorCode SNESGetSolutionUpdate(SNES snes, Vec *x)
5061: {
5062:   PetscFunctionBegin;
5064:   PetscAssertPointer(x, 2);
5065:   *x = snes->vec_sol_update;
5066:   PetscFunctionReturn(PETSC_SUCCESS);
5067: }
5069: /*@C
5070:   SNESGetFunction - Returns the function that defines the nonlinear system set with `SNESSetFunction()`
5072:   Not Collective, but `r` is parallel if `snes` is parallel. Collective if `r` is requested, but has not been created yet.
5074:   Input Parameter:
5075: . snes - the `SNES` context
5077:   Output Parameters:
5078: + r   - the vector that is used to store residuals (or `NULL` if you don't want it)
5079: . f   - the function (or `NULL` if you don't want it);  for calling sequence see `SNESFunctionFn`
5080: - ctx - the function context (or `NULL` if you don't want it)
5082:   Level: advanced
5084:   Note:
5085:   The vector `r` DOES NOT, in general, contain the current value of the `SNES` nonlinear function
5087: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESSetFunction()`, `SNESGetSolution()`, `SNESFunctionFn`
5088: @*/
5089: PetscErrorCode SNESGetFunction(SNES snes, Vec *r, SNESFunctionFn **f, void **ctx)
5090: {
5091:   DM dm;
5093:   PetscFunctionBegin;
5095:   if (r) {
5096:     if (!snes->vec_func) {
5097:       if (snes->vec_rhs) {
5098:         PetscCall(VecDuplicate(snes->vec_rhs, &snes->vec_func));
5099:       } else if (snes->vec_sol) {
5100:         PetscCall(VecDuplicate(snes->vec_sol, &snes->vec_func));
5101:       } else if (snes->dm) {
5102:         PetscCall(DMCreateGlobalVector(snes->dm, &snes->vec_func));
5103:       }
5104:     }
5105:     *r = snes->vec_func;
5106:   }
5107:   PetscCall(SNESGetDM(snes, &dm));
5108:   PetscCall(DMSNESGetFunction(dm, f, ctx));
5109:   PetscFunctionReturn(PETSC_SUCCESS);
5110: }
5112: /*@C
5113:   SNESGetNGS - Returns the function and context set with `SNESSetNGS()`
5115:   Input Parameter:
5116: . snes - the `SNES` context
5118:   Output Parameters:
5119: + f   - the function (or `NULL`) see `SNESNGSFn` for calling sequence
5120: - ctx - the function context (or `NULL`)
5122:   Level: advanced
5124: .seealso: [](ch_snes), `SNESSetNGS()`, `SNESGetFunction()`, `SNESNGSFn`
5125: @*/
5126: PetscErrorCode SNESGetNGS(SNES snes, SNESNGSFn **f, void **ctx)
5127: {
5128:   DM dm;
5130:   PetscFunctionBegin;
5132:   PetscCall(SNESGetDM(snes, &dm));
5133:   PetscCall(DMSNESGetNGS(dm, f, ctx));
5134:   PetscFunctionReturn(PETSC_SUCCESS);
5135: }
5137: /*@
5138:   SNESSetOptionsPrefix - Sets the prefix used for searching for all
5139:   `SNES` options in the database.
5141:   Logically Collective
5143:   Input Parameters:
5144: + snes   - the `SNES` context
5145: - prefix - the prefix to prepend to all option names
5147:   Level: advanced
5149:   Note:
5150:   A hyphen (-) must NOT be given at the beginning of the prefix name.
5151:   The first character of all runtime options is AUTOMATICALLY the hyphen.
5153: .seealso: [](ch_snes), `SNES`, `SNESSetFromOptions()`, `SNESAppendOptionsPrefix()`
5154: @*/
5155: PetscErrorCode SNESSetOptionsPrefix(SNES snes, const char prefix[])
5156: {
5157:   PetscFunctionBegin;
5159:   PetscCall(PetscObjectSetOptionsPrefix((PetscObject)snes, prefix));
5160:   if (!snes->ksp) PetscCall(SNESGetKSP(snes, &snes->ksp));
5161:   if (snes->linesearch) {
5162:     PetscCall(SNESGetLineSearch(snes, &snes->linesearch));
5163:     PetscCall(PetscObjectSetOptionsPrefix((PetscObject)snes->linesearch, prefix));
5164:   }
5165:   PetscCall(KSPSetOptionsPrefix(snes->ksp, prefix));
5166:   PetscFunctionReturn(PETSC_SUCCESS);
5167: }
5169: /*@
5170:   SNESAppendOptionsPrefix - Appends to the prefix used for searching for all
5171:   `SNES` options in the database.
5173:   Logically Collective
5175:   Input Parameters:
5176: + snes   - the `SNES` context
5177: - prefix - the prefix to prepend to all option names
5179:   Level: advanced
5181:   Note:
5182:   A hyphen (-) must NOT be given at the beginning of the prefix name.
5183:   The first character of all runtime options is AUTOMATICALLY the hyphen.
5185: .seealso: [](ch_snes), `SNESGetOptionsPrefix()`, `SNESSetOptionsPrefix()`
5186: @*/
5187: PetscErrorCode SNESAppendOptionsPrefix(SNES snes, const char prefix[])
5188: {
5189:   PetscFunctionBegin;
5191:   PetscCall(PetscObjectAppendOptionsPrefix((PetscObject)snes, prefix));
5192:   if (!snes->ksp) PetscCall(SNESGetKSP(snes, &snes->ksp));
5193:   if (snes->linesearch) {
5194:     PetscCall(SNESGetLineSearch(snes, &snes->linesearch));
5195:     PetscCall(PetscObjectAppendOptionsPrefix((PetscObject)snes->linesearch, prefix));
5196:   }
5197:   PetscCall(KSPAppendOptionsPrefix(snes->ksp, prefix));
5198:   PetscFunctionReturn(PETSC_SUCCESS);
5199: }
5201: /*@
5202:   SNESGetOptionsPrefix - Gets the prefix used for searching for all
5203:   `SNES` options in the database.
5205:   Not Collective
5207:   Input Parameter:
5208: . snes - the `SNES` context
5210:   Output Parameter:
5211: . prefix - pointer to the prefix string used
5213:   Level: advanced
5215:   Fortran Note:
5216:   The user should pass in a string 'prefix' of
5217:   sufficient length to hold the prefix.
5219: .seealso: [](ch_snes), `SNES`, `SNESSetOptionsPrefix()`, `SNESAppendOptionsPrefix()`
5220: @*/
5221: PetscErrorCode SNESGetOptionsPrefix(SNES snes, const char *prefix[])
5222: {
5223:   PetscFunctionBegin;
5225:   PetscCall(PetscObjectGetOptionsPrefix((PetscObject)snes, prefix));
5226:   PetscFunctionReturn(PETSC_SUCCESS);
5227: }
5229: /*@C
5230:   SNESRegister - Adds a method to the nonlinear solver package.
5232:   Not Collective
5234:   Input Parameters:
5235: + sname    - name of a new user-defined solver
5236: - function - routine to create method context
5238:   Level: advanced
5240:   Note:
5241:   `SNESRegister()` may be called multiple times to add several user-defined solvers.
5243:   Example Usage:
5244: .vb
5245:    SNESRegister("my_solver", MySolverCreate);
5246: .ve
5248:   Then, your solver can be chosen with the procedural interface via
5249: $     SNESSetType(snes, "my_solver")
5250:   or at runtime via the option
5251: $     -snes_type my_solver
5253: .seealso: [](ch_snes), `SNESRegisterAll()`, `SNESRegisterDestroy()`
5254: @*/
5255: PetscErrorCode SNESRegister(const char sname[], PetscErrorCode (*function)(SNES))
5256: {
5257:   PetscFunctionBegin;
5258:   PetscCall(SNESInitializePackage());
5259:   PetscCall(PetscFunctionListAdd(&SNESList, sname, function));
5260:   PetscFunctionReturn(PETSC_SUCCESS);
5261: }
5263: PetscErrorCode SNESTestLocalMin(SNES snes)
5264: {
5265:   PetscInt    N, i, j;
5266:   Vec         u, uh, fh;
5267:   PetscScalar value;
5268:   PetscReal   norm;
5270:   PetscFunctionBegin;
5271:   PetscCall(SNESGetSolution(snes, &u));
5272:   PetscCall(VecDuplicate(u, &uh));
5273:   PetscCall(VecDuplicate(u, &fh));
5275:   /* currently only works for sequential */
5276:   PetscCall(PetscPrintf(PetscObjectComm((PetscObject)snes), "Testing FormFunction() for local min\n"));
5277:   PetscCall(VecGetSize(u, &N));
5278:   for (i = 0; i < N; i++) {
5279:     PetscCall(VecCopy(u, uh));
5280:     PetscCall(PetscPrintf(PetscObjectComm((PetscObject)snes), "i = %" PetscInt_FMT "\n", i));
5281:     for (j = -10; j < 11; j++) {
5282:       value = PetscSign(j) * PetscExpReal(PetscAbs(j) - 10.0);
5283:       PetscCall(VecSetValue(uh, i, value, ADD_VALUES));
5284:       PetscCall(SNESComputeFunction(snes, uh, fh));
5285:       PetscCall(VecNorm(fh, NORM_2, &norm));
5286:       PetscCall(PetscPrintf(PetscObjectComm((PetscObject)snes), "       j norm %" PetscInt_FMT " %18.16e\n", j, (double)norm));
5287:       value = -value;
5288:       PetscCall(VecSetValue(uh, i, value, ADD_VALUES));
5289:     }
5290:   }
5291:   PetscCall(VecDestroy(&uh));
5292:   PetscCall(VecDestroy(&fh));
5293:   PetscFunctionReturn(PETSC_SUCCESS);
5294: }
5296: /*@
5297:   SNESKSPSetUseEW - Sets `SNES` to the use Eisenstat-Walker method for
5298:   computing relative tolerance for linear solvers within an inexact
5299:   Newton method.
5301:   Logically Collective
5303:   Input Parameters:
5304: + snes - `SNES` context
5305: - flag - `PETSC_TRUE` or `PETSC_FALSE`
5307:   Options Database Keys:
5308: + -snes_ksp_ew                       - use Eisenstat-Walker method for determining linear system convergence
5309: . -snes_ksp_ew_version ver           - version of  Eisenstat-Walker method
5310: . -snes_ksp_ew_rtol0 <rtol0>         - Sets rtol0
5311: . -snes_ksp_ew_rtolmax <rtolmax>     - Sets rtolmax
5312: . -snes_ksp_ew_gamma <gamma>         - Sets gamma
5313: . -snes_ksp_ew_alpha <alpha>         - Sets alpha
5314: . -snes_ksp_ew_alpha2 <alpha2>       - Sets alpha2
5315: - -snes_ksp_ew_threshold <threshold> - Sets threshold
5317:   Level: advanced
5319:   Note:
5320:   The default is to use a constant relative tolerance for
5321:   the inner linear solvers.  Alternatively, one can use the
5322:   Eisenstat-Walker method {cite}`ew96`, where the relative convergence tolerance
5323:   is reset at each Newton iteration according progress of the nonlinear
5324:   solver.
5326: .seealso: [](ch_snes), `KSP`, `SNES`, `SNESKSPGetUseEW()`, `SNESKSPGetParametersEW()`, `SNESKSPSetParametersEW()`
5327: @*/
5328: PetscErrorCode SNESKSPSetUseEW(SNES snes, PetscBool flag)
5329: {
5330:   PetscFunctionBegin;
5333:   snes->ksp_ewconv = flag;
5334:   PetscFunctionReturn(PETSC_SUCCESS);
5335: }
5337: /*@
5338:   SNESKSPGetUseEW - Gets if `SNES` is using Eisenstat-Walker method
5339:   for computing relative tolerance for linear solvers within an
5340:   inexact Newton method.
5342:   Not Collective
5344:   Input Parameter:
5345: . snes - `SNES` context
5347:   Output Parameter:
5348: . flag - `PETSC_TRUE` or `PETSC_FALSE`
5350:   Level: advanced
5352: .seealso: [](ch_snes), `SNESKSPSetUseEW()`, `SNESKSPGetParametersEW()`, `SNESKSPSetParametersEW()`
5353: @*/
5354: PetscErrorCode SNESKSPGetUseEW(SNES snes, PetscBool *flag)
5355: {
5356:   PetscFunctionBegin;
5358:   PetscAssertPointer(flag, 2);
5359:   *flag = snes->ksp_ewconv;
5360:   PetscFunctionReturn(PETSC_SUCCESS);
5361: }
5363: /*@
5364:   SNESKSPSetParametersEW - Sets parameters for Eisenstat-Walker
5365:   convergence criteria for the linear solvers within an inexact
5366:   Newton method.
5368:   Logically Collective
5370:   Input Parameters:
5371: + snes      - `SNES` context
5372: . version   - version 1, 2 (default is 2), 3 or 4
5373: . rtol_0    - initial relative tolerance (0 <= rtol_0 < 1)
5374: . rtol_max  - maximum relative tolerance (0 <= rtol_max < 1)
5375: . gamma     - multiplicative factor for version 2 rtol computation
5376:              (0 <= gamma2 <= 1)
5377: . alpha     - power for version 2 rtol computation (1 < alpha <= 2)
5378: . alpha2    - power for safeguard
5379: - threshold - threshold for imposing safeguard (0 < threshold < 1)
5381:   Level: advanced
5383:   Notes:
5384:   Version 3 was contributed by Luis Chacon, June 2006.
5386:   Use `PETSC_CURRENT` to retain the default for any of the parameters.
5388: .seealso: [](ch_snes), `SNES`, `SNESKSPSetUseEW()`, `SNESKSPGetUseEW()`, `SNESKSPGetParametersEW()`
5389: @*/
5390: PetscErrorCode SNESKSPSetParametersEW(SNES snes, PetscInt version, PetscReal rtol_0, PetscReal rtol_max, PetscReal gamma, PetscReal alpha, PetscReal alpha2, PetscReal threshold)
5391: {
5392:   SNESKSPEW *kctx;
5394:   PetscFunctionBegin;
5396:   kctx = (SNESKSPEW *)snes->kspconvctx;
5397:   PetscCheck(kctx, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "No Eisenstat-Walker context existing");
5406:   if (version != PETSC_CURRENT) kctx->version = version;
5407:   if (rtol_0 != (PetscReal)PETSC_CURRENT) kctx->rtol_0 = rtol_0;
5408:   if (rtol_max != (PetscReal)PETSC_CURRENT) kctx->rtol_max = rtol_max;
5409:   if (gamma != (PetscReal)PETSC_CURRENT) kctx->gamma = gamma;
5410:   if (alpha != (PetscReal)PETSC_CURRENT) kctx->alpha = alpha;
5411:   if (alpha2 != (PetscReal)PETSC_CURRENT) kctx->alpha2 = alpha2;
5412:   if (threshold != (PetscReal)PETSC_CURRENT) kctx->threshold = threshold;
5414:   PetscCheck(kctx->version >= 1 && kctx->version <= 4, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Only versions 1 to 4 are supported: %" PetscInt_FMT, kctx->version);
5415:   PetscCheck(kctx->rtol_0 >= 0.0 && kctx->rtol_0 < 1.0, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "0.0 <= rtol_0 < 1.0: %g", (double)kctx->rtol_0);
5416:   PetscCheck(kctx->rtol_max >= 0.0 && kctx->rtol_max < 1.0, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "0.0 <= rtol_max (%g) < 1.0", (double)kctx->rtol_max);
5417:   PetscCheck(kctx->gamma >= 0.0 && kctx->gamma <= 1.0, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "0.0 <= gamma (%g) <= 1.0", (double)kctx->gamma);
5418:   PetscCheck(kctx->alpha > 1.0 && kctx->alpha <= 2.0, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "1.0 < alpha (%g) <= 2.0", (double)kctx->alpha);
5419:   PetscCheck(kctx->threshold > 0.0 && kctx->threshold < 1.0, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "0.0 < threshold (%g) < 1.0", (double)kctx->threshold);
5420:   PetscFunctionReturn(PETSC_SUCCESS);
5421: }
5423: /*@
5424:   SNESKSPGetParametersEW - Gets parameters for Eisenstat-Walker
5425:   convergence criteria for the linear solvers within an inexact
5426:   Newton method.
5428:   Not Collective
5430:   Input Parameter:
5431: . snes - `SNES` context
5433:   Output Parameters:
5434: + version   - version 1, 2 (default is 2), 3 or 4
5435: . rtol_0    - initial relative tolerance (0 <= rtol_0 < 1)
5436: . rtol_max  - maximum relative tolerance (0 <= rtol_max < 1)
5437: . gamma     - multiplicative factor for version 2 rtol computation (0 <= gamma2 <= 1)
5438: . alpha     - power for version 2 rtol computation (1 < alpha <= 2)
5439: . alpha2    - power for safeguard
5440: - threshold - threshold for imposing safeguard (0 < threshold < 1)
5442:   Level: advanced
5444: .seealso: [](ch_snes), `SNES`, `SNESKSPSetUseEW()`, `SNESKSPGetUseEW()`, `SNESKSPSetParametersEW()`
5445: @*/
5446: PetscErrorCode SNESKSPGetParametersEW(SNES snes, PetscInt *version, PetscReal *rtol_0, PetscReal *rtol_max, PetscReal *gamma, PetscReal *alpha, PetscReal *alpha2, PetscReal *threshold)
5447: {
5448:   SNESKSPEW *kctx;
5450:   PetscFunctionBegin;
5452:   kctx = (SNESKSPEW *)snes->kspconvctx;
5453:   PetscCheck(kctx, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "No Eisenstat-Walker context existing");
5454:   if (version) *version = kctx->version;
5455:   if (rtol_0) *rtol_0 = kctx->rtol_0;
5456:   if (rtol_max) *rtol_max = kctx->rtol_max;
5457:   if (gamma) *gamma = kctx->gamma;
5458:   if (alpha) *alpha = kctx->alpha;
5459:   if (alpha2) *alpha2 = kctx->alpha2;
5460:   if (threshold) *threshold = kctx->threshold;
5461:   PetscFunctionReturn(PETSC_SUCCESS);
5462: }
5464: PetscErrorCode KSPPreSolve_SNESEW(KSP ksp, Vec b, Vec x, void *ctx)
5465: {
5466:   SNES       snes = (SNES)ctx;
5467:   SNESKSPEW *kctx = (SNESKSPEW *)snes->kspconvctx;
5468:   PetscReal  rtol = PETSC_CURRENT, stol;
5470:   PetscFunctionBegin;
5471:   if (!snes->ksp_ewconv) PetscFunctionReturn(PETSC_SUCCESS);
5472:   if (!snes->iter) {
5473:     rtol = kctx->rtol_0; /* first time in, so use the original user rtol */
5474:     PetscCall(VecNorm(snes->vec_func, NORM_2, &kctx->norm_first));
5475:   } else {
5476:     PetscCheck(kctx->version >= 1 && kctx->version <= 4, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Only versions 1-4 are supported: %" PetscInt_FMT, kctx->version);
5477:     if (kctx->version == 1) {
5478:       rtol = PetscAbsReal(snes->norm - kctx->lresid_last) / kctx->norm_last;
5479:       stol = PetscPowReal(kctx->rtol_last, kctx->alpha2);
5480:       if (stol > kctx->threshold) rtol = PetscMax(rtol, stol);
5481:     } else if (kctx->version == 2) {
5482:       rtol = kctx->gamma * PetscPowReal(snes->norm / kctx->norm_last, kctx->alpha);
5483:       stol = kctx->gamma * PetscPowReal(kctx->rtol_last, kctx->alpha);
5484:       if (stol > kctx->threshold) rtol = PetscMax(rtol, stol);
5485:     } else if (kctx->version == 3) { /* contributed by Luis Chacon, June 2006. */
5486:       rtol = kctx->gamma * PetscPowReal(snes->norm / kctx->norm_last, kctx->alpha);
5487:       /* safeguard: avoid sharp decrease of rtol */
5488:       stol = kctx->gamma * PetscPowReal(kctx->rtol_last, kctx->alpha);
5489:       stol = PetscMax(rtol, stol);
5490:       rtol = PetscMin(kctx->rtol_0, stol);
5491:       /* safeguard: avoid oversolving */
5492:       stol = kctx->gamma * (kctx->norm_first * snes->rtol) / snes->norm;
5493:       stol = PetscMax(rtol, stol);
5494:       rtol = PetscMin(kctx->rtol_0, stol);
5495:     } else /* if (kctx->version == 4) */ {
5496:       /* H.-B. An et al. Journal of Computational and Applied Mathematics 200 (2007) 47-60 */
5497:       PetscReal ared = PetscAbsReal(kctx->norm_last - snes->norm);
5498:       PetscReal pred = PetscAbsReal(kctx->norm_last - kctx->lresid_last);
5499:       PetscReal rk   = ared / pred;
5500:       if (rk < kctx->v4_p1) rtol = 1. - 2. * kctx->v4_p1;
5501:       else if (rk < kctx->v4_p2) rtol = kctx->rtol_last;
5502:       else if (rk < kctx->v4_p3) rtol = kctx->v4_m1 * kctx->rtol_last;
5503:       else rtol = kctx->v4_m2 * kctx->rtol_last;
5505:       if (kctx->rtol_last_2 > kctx->v4_m3 && kctx->rtol_last > kctx->v4_m3 && kctx->rk_last_2 < kctx->v4_p1 && kctx->rk_last < kctx->v4_p1) rtol = kctx->v4_m4 * kctx->rtol_last;
5506:       kctx->rtol_last_2 = kctx->rtol_last;
5507:       kctx->rk_last_2   = kctx->rk_last;
5508:       kctx->rk_last     = rk;
5509:     }
5510:   }
5511:   /* safeguard: avoid rtol greater than rtol_max */
5512:   rtol = PetscMin(rtol, kctx->rtol_max);
5513:   PetscCall(KSPSetTolerances(ksp, rtol, PETSC_CURRENT, PETSC_CURRENT, PETSC_CURRENT));
5514:   PetscCall(PetscInfo(snes, "iter %" PetscInt_FMT ", Eisenstat-Walker (version %" PetscInt_FMT ") KSP rtol=%g\n", snes->iter, kctx->version, (double)rtol));
5515:   PetscFunctionReturn(PETSC_SUCCESS);
5516: }
5518: PetscErrorCode KSPPostSolve_SNESEW(KSP ksp, Vec b, Vec x, void *ctx)
5519: {
5520:   SNES       snes = (SNES)ctx;
5521:   SNESKSPEW *kctx = (SNESKSPEW *)snes->kspconvctx;
5522:   PCSide     pcside;
5523:   Vec        lres;
5525:   PetscFunctionBegin;
5526:   if (!snes->ksp_ewconv) PetscFunctionReturn(PETSC_SUCCESS);
5527:   PetscCall(KSPGetTolerances(ksp, &kctx->rtol_last, NULL, NULL, NULL));
5528:   kctx->norm_last = snes->norm;
5529:   if (kctx->version == 1 || kctx->version == 4) {
5530:     PC        pc;
5531:     PetscBool getRes;
5533:     PetscCall(KSPGetPC(ksp, &pc));
5534:     PetscCall(PetscObjectTypeCompare((PetscObject)pc, PCNONE, &getRes));
5535:     if (!getRes) {
5536:       KSPNormType normtype;
5538:       PetscCall(KSPGetNormType(ksp, &normtype));
5539:       getRes = (PetscBool)(normtype == KSP_NORM_UNPRECONDITIONED);
5540:     }
5541:     PetscCall(KSPGetPCSide(ksp, &pcside));
5542:     if (pcside == PC_RIGHT || getRes) { /* KSP residual is true linear residual */
5543:       PetscCall(KSPGetResidualNorm(ksp, &kctx->lresid_last));
5544:     } else {
5545:       /* KSP residual is preconditioned residual */
5546:       /* compute true linear residual norm */
5547:       Mat J;
5548:       PetscCall(KSPGetOperators(ksp, &J, NULL));
5549:       PetscCall(VecDuplicate(b, &lres));
5550:       PetscCall(MatMult(J, x, lres));
5551:       PetscCall(VecAYPX(lres, -1.0, b));
5552:       PetscCall(VecNorm(lres, NORM_2, &kctx->lresid_last));
5553:       PetscCall(VecDestroy(&lres));
5554:     }
5555:   }
5556:   PetscFunctionReturn(PETSC_SUCCESS);
5557: }
5559: /*@
5560:   SNESGetKSP - Returns the `KSP` context for a `SNES` solver.
5562:   Not Collective, but if `snes` is parallel, then `ksp` is parallel
5564:   Input Parameter:
5565: . snes - the `SNES` context
5567:   Output Parameter:
5568: . ksp - the `KSP` context
5570:   Level: beginner
5572:   Notes:
5573:   The user can then directly manipulate the `KSP` context to set various
5574:   options, etc.  Likewise, the user can then extract and manipulate the
5575:   `PC` contexts as well.
5577:   Some `SNESType`s do not use a `KSP` but a `KSP` is still returned by this function, changes to that `KSP` will have no effect.
5579: .seealso: [](ch_snes), `SNES`, `KSP`, `PC`, `KSPGetPC()`, `SNESCreate()`, `KSPCreate()`, `SNESSetKSP()`
5580: @*/
5581: PetscErrorCode SNESGetKSP(SNES snes, KSP *ksp)
5582: {
5583:   PetscFunctionBegin;
5585:   PetscAssertPointer(ksp, 2);
5587:   if (!snes->ksp) {
5588:     PetscCall(KSPCreate(PetscObjectComm((PetscObject)snes), &snes->ksp));
5589:     PetscCall(PetscObjectIncrementTabLevel((PetscObject)snes->ksp, (PetscObject)snes, 1));
5591:     PetscCall(KSPSetPreSolve(snes->ksp, KSPPreSolve_SNESEW, snes));
5592:     PetscCall(KSPSetPostSolve(snes->ksp, KSPPostSolve_SNESEW, snes));
5594:     PetscCall(KSPMonitorSetFromOptions(snes->ksp, "-snes_monitor_ksp", "snes_preconditioned_residual", snes));
5595:     PetscCall(PetscObjectSetOptions((PetscObject)snes->ksp, ((PetscObject)snes)->options));
5596:   }
5597:   *ksp = snes->ksp;
5598:   PetscFunctionReturn(PETSC_SUCCESS);
5599: }
5601: #include <petsc/private/dmimpl.h>
5602: /*@
5603:   SNESSetDM - Sets the `DM` that may be used by some `SNES` nonlinear solvers or their underlying preconditioners
5605:   Logically Collective
5607:   Input Parameters:
5608: + snes - the nonlinear solver context
5609: - dm   - the `DM`, cannot be `NULL`
5611:   Level: intermediate
5613:   Note:
5614:   A `DM` can only be used for solving one problem at a time because information about the problem is stored on the `DM`,
5615:   even when not using interfaces like `DMSNESSetFunction()`.  Use `DMClone()` to get a distinct `DM` when solving different
5616:   problems using the same function space.
5618: .seealso: [](ch_snes), `DM`, `SNES`, `SNESGetDM()`, `KSPSetDM()`, `KSPGetDM()`
5619: @*/
5620: PetscErrorCode SNESSetDM(SNES snes, DM dm)
5621: {
5622:   KSP    ksp;
5623:   DMSNES sdm;
5625:   PetscFunctionBegin;
5628:   PetscCall(PetscObjectReference((PetscObject)dm));
5629:   if (snes->dm) { /* Move the DMSNES context over to the new DM unless the new DM already has one */
5630:     if (snes->dm->dmsnes && !dm->dmsnes) {
5631:       PetscCall(DMCopyDMSNES(snes->dm, dm));
5632:       PetscCall(DMGetDMSNES(snes->dm, &sdm));
5633:       if (sdm->originaldm == snes->dm) sdm->originaldm = dm; /* Grant write privileges to the replacement DM */
5634:     }
5635:     PetscCall(DMCoarsenHookRemove(snes->dm, DMCoarsenHook_SNESVecSol, DMRestrictHook_SNESVecSol, snes));
5636:     PetscCall(DMDestroy(&snes->dm));
5637:   }
5638:   snes->dm     = dm;
5639:   snes->dmAuto = PETSC_FALSE;
5641:   PetscCall(SNESGetKSP(snes, &ksp));
5642:   PetscCall(KSPSetDM(ksp, dm));
5643:   PetscCall(KSPSetDMActive(ksp, PETSC_FALSE));
5644:   if (snes->npc) {
5645:     PetscCall(SNESSetDM(snes->npc, snes->dm));
5646:     PetscCall(SNESSetNPCSide(snes, snes->npcside));
5647:   }
5648:   PetscFunctionReturn(PETSC_SUCCESS);
5649: }
5651: /*@
5652:   SNESGetDM - Gets the `DM` that may be used by some `SNES` nonlinear solvers/preconditioners
5654:   Not Collective but `dm` obtained is parallel on `snes`
5656:   Input Parameter:
5657: . snes - the `SNES` context
5659:   Output Parameter:
5660: . dm - the `DM`
5662:   Level: intermediate
5664: .seealso: [](ch_snes), `DM`, `SNES`, `SNESSetDM()`, `KSPSetDM()`, `KSPGetDM()`
5665: @*/
5666: PetscErrorCode SNESGetDM(SNES snes, DM *dm)
5667: {
5668:   PetscFunctionBegin;
5670:   if (!snes->dm) {
5671:     PetscCall(DMShellCreate(PetscObjectComm((PetscObject)snes), &snes->dm));
5672:     snes->dmAuto = PETSC_TRUE;
5673:   }
5674:   *dm = snes->dm;
5675:   PetscFunctionReturn(PETSC_SUCCESS);
5676: }
5678: /*@
5679:   SNESSetNPC - Sets the nonlinear preconditioner to be used.
5681:   Collective
5683:   Input Parameters:
5684: + snes - iterative context obtained from `SNESCreate()`
5685: - npc  - the `SNES` nonlinear preconditioner object
5687:   Options Database Key:
5688: . -npc_snes_type <type> - set the type of the `SNES` to use as the nonlinear preconditioner
5690:   Level: developer
5692:   Notes:
5693:   This is rarely used, rather use `SNESGetNPC()` to retrieve the preconditioner and configure it using the API.
5695:   Only some `SNESType` can use a nonlinear preconditioner
5697: .seealso: [](ch_snes), `SNES`, `SNESNGS`, `SNESFAS`, `SNESGetNPC()`, `SNESHasNPC()`
5698: @*/
5699: PetscErrorCode SNESSetNPC(SNES snes, SNES npc)
5700: {
5701:   PetscFunctionBegin;
5704:   PetscCheckSameComm(snes, 1, npc, 2);
5705:   PetscCall(PetscObjectReference((PetscObject)npc));
5706:   PetscCall(SNESDestroy(&snes->npc));
5707:   snes->npc = npc;
5708:   PetscFunctionReturn(PETSC_SUCCESS);
5709: }
5711: /*@
5712:   SNESGetNPC - Gets a nonlinear preconditioning solver SNES` to be used to precondition the original nonlinear solver.
5714:   Not Collective; but any changes to the obtained the `pc` object must be applied collectively
5716:   Input Parameter:
5717: . snes - iterative context obtained from `SNESCreate()`
5719:   Output Parameter:
5720: . pc - the `SNES` preconditioner context
5722:   Options Database Key:
5723: . -npc_snes_type <type> - set the type of the `SNES` to use as the nonlinear preconditioner
5725:   Level: advanced
5727:   Notes:
5728:   If a `SNES` was previously set with `SNESSetNPC()` then that value is returned, otherwise a new `SNES` object is created that will
5729:   be used as the nonlinear preconditioner for the current `SNES`.
5731:   The (preconditioner) `SNES` returned automatically inherits the same nonlinear function and Jacobian supplied to the original
5732:   `SNES`. These may be overwritten if needed.
5734:   Use the options database prefixes `-npc_snes`, `-npc_ksp`, etc., to control the configuration of the nonlinear preconditioner
5736: .seealso: [](ch_snes), `SNESSetNPC()`, `SNESHasNPC()`, `SNES`, `SNESCreate()`
5737: @*/
5738: PetscErrorCode SNESGetNPC(SNES snes, SNES *pc)
5739: {
5740:   const char *optionsprefix;
5742:   PetscFunctionBegin;
5744:   PetscAssertPointer(pc, 2);
5745:   if (!snes->npc) {
5746:     void *ctx;
5748:     PetscCall(SNESCreate(PetscObjectComm((PetscObject)snes), &snes->npc));
5749:     PetscCall(PetscObjectIncrementTabLevel((PetscObject)snes->npc, (PetscObject)snes, 1));
5750:     PetscCall(SNESGetOptionsPrefix(snes, &optionsprefix));
5751:     PetscCall(SNESSetOptionsPrefix(snes->npc, optionsprefix));
5752:     PetscCall(SNESAppendOptionsPrefix(snes->npc, "npc_"));
5753:     if (snes->ops->usercompute) {
5754:       PetscCall(SNESSetComputeApplicationContext(snes, snes->ops->usercompute, snes->ops->userdestroy));
5755:     } else {
5756:       PetscCall(SNESGetApplicationContext(snes, &ctx));
5757:       PetscCall(SNESSetApplicationContext(snes->npc, ctx));
5758:     }
5759:     PetscCall(SNESSetCountersReset(snes->npc, PETSC_FALSE));
5760:   }
5761:   *pc = snes->npc;
5762:   PetscFunctionReturn(PETSC_SUCCESS);
5763: }
5765: /*@
5766:   SNESHasNPC - Returns whether a nonlinear preconditioner is associated with the given `SNES`
5768:   Not Collective
5770:   Input Parameter:
5771: . snes - iterative context obtained from `SNESCreate()`
5773:   Output Parameter:
5774: . has_npc - whether the `SNES` has a nonlinear preconditioner or not
5776:   Level: developer
5778: .seealso: [](ch_snes), `SNESSetNPC()`, `SNESGetNPC()`
5779: @*/
5780: PetscErrorCode SNESHasNPC(SNES snes, PetscBool *has_npc)
5781: {
5782:   PetscFunctionBegin;
5784:   *has_npc = (PetscBool)(snes->npc ? PETSC_TRUE : PETSC_FALSE);
5785:   PetscFunctionReturn(PETSC_SUCCESS);
5786: }
5788: /*@
5789:   SNESSetNPCSide - Sets the nonlinear preconditioning side used by the nonlinear preconditioner inside `SNES`.
5791:   Logically Collective
5793:   Input Parameter:
5794: . snes - iterative context obtained from `SNESCreate()`
5796:   Output Parameter:
5797: . side - the preconditioning side, where side is one of
5798: .vb
5799:       PC_LEFT  - left preconditioning
5800:       PC_RIGHT - right preconditioning (default for most nonlinear solvers)
5801: .ve
5803:   Options Database Key:
5804: . -snes_npc_side <right,left> - nonlinear preconditioner side
5806:   Level: intermediate
5808:   Note:
5809:   `SNESNRICHARDSON` and `SNESNCG` only support left preconditioning.
5811: .seealso: [](ch_snes), `SNES`, `SNESGetNPC()`, `SNESNRICHARDSON`, `SNESNCG`, `SNESType`, `SNESGetNPCSide()`, `KSPSetPCSide()`, `PC_LEFT`, `PC_RIGHT`, `PCSide`
5812: @*/
5813: PetscErrorCode SNESSetNPCSide(SNES snes, PCSide side)
5814: {
5815:   PetscFunctionBegin;
5818:   if (side == PC_SIDE_DEFAULT) side = PC_RIGHT;
5819:   PetscCheck((side == PC_LEFT) || (side == PC_RIGHT), PetscObjectComm((PetscObject)snes), PETSC_ERR_ARG_WRONG, "Only PC_LEFT and PC_RIGHT are supported");
5820:   snes->npcside = side;
5821:   PetscFunctionReturn(PETSC_SUCCESS);
5822: }
5824: /*@
5825:   SNESGetNPCSide - Gets the preconditioning side used by the nonlinear preconditioner inside `SNES`.
5827:   Not Collective
5829:   Input Parameter:
5830: . snes - iterative context obtained from `SNESCreate()`
5832:   Output Parameter:
5833: . side - the preconditioning side, where side is one of
5834: .vb
5835:       `PC_LEFT` - left preconditioning
5836:       `PC_RIGHT` - right preconditioning (default for most nonlinear solvers)
5837: .ve
5839:   Level: intermediate
5841: .seealso: [](ch_snes), `SNES`, `SNESGetNPC()`, `SNESSetNPCSide()`, `KSPGetPCSide()`, `PC_LEFT`, `PC_RIGHT`, `PCSide`
5842: @*/
5843: PetscErrorCode SNESGetNPCSide(SNES snes, PCSide *side)
5844: {
5845:   PetscFunctionBegin;
5847:   PetscAssertPointer(side, 2);
5848:   *side = snes->npcside;
5849:   PetscFunctionReturn(PETSC_SUCCESS);
5850: }
5852: /*@
5853:   SNESSetLineSearch - Sets the `SNESLineSearch` to be used for a given `SNES`
5855:   Collective
5857:   Input Parameters:
5858: + snes       - iterative context obtained from `SNESCreate()`
5859: - linesearch - the linesearch object
5861:   Level: developer
5863:   Note:
5864:   This is almost never used, rather one uses `SNESGetLineSearch()` to retrieve the line search and set options on it
5865:   to configure it using the API).
5867: .seealso: [](ch_snes), `SNES`, `SNESLineSearch`, `SNESGetLineSearch()`
5868: @*/
5869: PetscErrorCode SNESSetLineSearch(SNES snes, SNESLineSearch linesearch)
5870: {
5871:   PetscFunctionBegin;
5874:   PetscCheckSameComm(snes, 1, linesearch, 2);
5875:   PetscCall(PetscObjectReference((PetscObject)linesearch));
5876:   PetscCall(SNESLineSearchDestroy(&snes->linesearch));
5878:   snes->linesearch = linesearch;
5879:   PetscFunctionReturn(PETSC_SUCCESS);
5880: }
5882: /*@
5883:   SNESGetLineSearch - Returns the line search associated with the `SNES`.
5885:   Not Collective
5887:   Input Parameter:
5888: . snes - iterative context obtained from `SNESCreate()`
5890:   Output Parameter:
5891: . linesearch - linesearch context
5893:   Level: beginner
5895:   Notes:
5896:   It creates a default line search instance which can be configured as needed in case it has not been already set with `SNESSetLineSearch()`.
5898:   You can also use the options database keys `-snes_linesearch_*` to configure the line search. See `SNESLineSearchSetFromOptions()` for the possible options.
5900: .seealso: [](ch_snes), `SNESLineSearch`, `SNESSetLineSearch()`, `SNESLineSearchCreate()`, `SNESLineSearchSetFromOptions()`
5901: @*/
5902: PetscErrorCode SNESGetLineSearch(SNES snes, SNESLineSearch *linesearch)
5903: {
5904:   const char *optionsprefix;
5906:   PetscFunctionBegin;
5908:   PetscAssertPointer(linesearch, 2);
5909:   if (!snes->linesearch) {
5910:     PetscCall(SNESGetOptionsPrefix(snes, &optionsprefix));
5911:     PetscCall(SNESLineSearchCreate(PetscObjectComm((PetscObject)snes), &snes->linesearch));
5912:     PetscCall(SNESLineSearchSetSNES(snes->linesearch, snes));
5913:     PetscCall(SNESLineSearchAppendOptionsPrefix(snes->linesearch, optionsprefix));
5914:     PetscCall(PetscObjectIncrementTabLevel((PetscObject)snes->linesearch, (PetscObject)snes, 1));
5915:   }
5916:   *linesearch = snes->linesearch;
5917:   PetscFunctionReturn(PETSC_SUCCESS);
5918: }