petsc-3.10.5 2019-03-28
KSPSetNormType
Sets the norm that is used for convergence testing.
Synopsis
#include "petscksp.h"
PetscErrorCode KSPSetNormType(KSP ksp,KSPNormType normtype)
Logically Collective on KSP
Input Parameter
| ksp | - Krylov solver context
|
| normtype | - one of
|
KSP_NORM_NONE - skips computing the norm, this should only be used if you are using
the Krylov method as a smoother with a fixed small number of iterations.
Implicitly sets KSPConvergedSkip as KSP convergence test.
KSP_NORM_PRECONDITIONED - the default for left preconditioned solves, uses the l2 norm
of the preconditioned residual P^{-1}(b - A x)
KSP_NORM_UNPRECONDITIONED - uses the l2 norm of the true b - Ax residual.
KSP_NORM_NATURAL - supported by KSPCG, KSPCR, KSPCGNE, KSPCGS
Options Database Key
-ksp_norm_type <none,preconditioned,unpreconditioned,natural> -
Notes:
Not all combinations of preconditioner side (see KSPSetPCSide()) and norm type are supported by all Krylov methods.
If only one is set, PETSc tries to automatically change the other to find a compatible pair. If no such combination
is supported, PETSc will generate an error.
Developer Notes
Supported combinations of norm and preconditioner side are set using KSPSetSupportedNorm().
Keywords
KSP, create, context, norms
See Also
KSPSetUp(), KSPSolve(), KSPDestroy(), KSPConvergedSkip(), KSPSetCheckNormIteration(), KSPSetPCSide(), KSPGetPCSide(), KSPNormType
Level
advanced
Location
src/ksp/ksp/interface/itcreate.c
Index of all KSP routines
Table of Contents for all manual pages
Index of all manual pages