KSPSetCheckNormIteration#

Sets the first iteration at which the norm of the residual will be computed and used in the convergence test.

Synopsis#

#include "petscksp.h" 
PetscErrorCode KSPSetCheckNormIteration(KSP ksp, PetscInt it)

Logically Collective

Input Parameters#

  • ksp - Krylov solver context

  • it - use -1 to check at all iterations

Notes#

Currently only works with KSPCG, KSPBCGS and KSPIBCGS

Use KSPSetNormType(ksp,KSP_NORM_NONE) to never check the norm

On steps where the norm is not computed, the previous norm is still in the variable, so if you run with, for example, -ksp_monitor the residual norm will appear to be unchanged for several iterations (though it is not really unchanged).

See Also#

KSP, KSPSetUp(), KSPSolve(), KSPDestroy(), KSPConvergedSkip(), KSPSetNormType()

Level#

advanced

Location#

src/ksp/ksp/interface/itcreate.c


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