SNESNewtonTRSetUpdateParameters#
Sets the trust region update parameters.
Synopsis#
#include "petscsnes.h"   
PetscErrorCode SNESNewtonTRSetUpdateParameters(SNES snes, PetscReal eta1, PetscReal eta2, PetscReal eta3, PetscReal t1, PetscReal t2)
Logically Collective
Input Parameters#
- snes - the - SNEScontext
- eta1 - acceptance tolerance 
- eta2 - shrinking tolerance 
- eta3 - enlarging tolerance 
- t1 - shrink factor 
- t2 - enlarge factor 
Options Database Key#
- -snes_tr_eta1 - - Set eta1
- -snes_tr_eta2 - - Set eta2
- -snes_tr_eta3 - - Set eta3
- -snes_tr_t1 - - Set t1
- -snes_tr_t2 - - Set t2
Notes#
Given the ratio \(\rho = \frac{f(x_k) - f(x_k+s_k)}{m(0) - m(s_k)}\), with \(x_k\) the current iterate,
\(s_k\) the computed step, \(f\) the objective function, and \(m\) the quadratic model, the trust region
radius is modified as follows
$\(
\delta =
\begin{cases}
\delta * t_1 ,& \rho < \eta_2 \\
\delta * t_2 ,& \rho > \eta_3 \\
\end{cases}
\)\(
The step is accepted if \)\rho > \eta_1$.
Use PETSC_DETERMINE to use the default value for the given SNES.
Use PETSC_CURRENT to retain a value.
Fortran Note#
Use PETSC_DETERMINE_REAL, PETSC_CURRENT_REAL
See Also#
SNES: Nonlinear Solvers, SNES, SNESNEWTONTR, SNESSetObjective(), SNESNewtonTRGetUpdateParameters()
Level#
intermediate
Location#
Index of all SNES routines
Table of Contents for all manual pages
Index of all manual pages