KSPGMRES#
Implements the Generalized Minimal Residual method [SS86] with restart for solving linear systems using KSP.
Options Database Keys#
- -ksp_gmres_restart - - the number of Krylov directions to orthogonalize against
- -ksp_gmres_haptol - - sets the tolerance for happy ending (exact convergence) of GMRES- KSPGMRES
- -ksp_gmres_preallocate - preallocate all the Krylov search directions initially (otherwise groups of vectors are allocated as needed) 
- -ksp_gmres_classicalgramschmidt - use classical (unmodified) Gram-Schmidt to orthogonalize against the Krylov space (fast) (the default) 
- -ksp_gmres_modifiedgramschmidt - use modified Gram-Schmidt in the orthogonalization (more stable, but slower) 
- -ksp_gmres_cgs_refinement_type <refine_never,refine_ifneeded,refine_always> - determine if iterative refinement is used to increase the stability of the classical Gram-Schmidt orthogonalization. 
- -ksp_gmres_krylov_monitor - plot the Krylov space generated 
Note#
Left and right preconditioning are supported, but not symmetric preconditioning.
References#
Y. Saad and M. Schultz. GMRES: A generalized minimal residual algorithm for solving nonsymmetric linear systems. SIAM Journal on Scientific and Statistical Computing, 44:856–869, 1986.
See Also#
KSP: Linear System Solvers, KSPCreate(), KSPSetType(), KSPType, KSP, KSPFGMRES, KSPLGMRES, KSPPGMRES, KSPAGMRES, KSPDGMRES, KSPPIPEFGMRES,
KSPGMRESSetRestart(), KSPGMRESSetHapTol(), KSPGMRESSetPreAllocateVectors(), KSPGMRESSetOrthogonalization(), KSPGMRESGetOrthogonalization(),
KSPGMRESClassicalGramSchmidtOrthogonalization(), KSPGMRESModifiedGramSchmidtOrthogonalization(),
KSPGMRESCGSRefinementType, KSPGMRESSetCGSRefinementType(), KSPGMRESGetCGSRefinementType(), KSPGMRESMonitorKrylov(), KSPSetPCSide()
Level#
beginner
Location#
Examples#
src/ksp/ksp/tutorials/ex7.c
src/ksp/ksp/tutorials/ex62.c
src/tao/pde_constrained/tutorials/hyperbolic.c
src/ksp/ksp/tutorials/ex8.c
Index of all KSP routines
Table of Contents for all manual pages
Index of all manual pages