KSPGetConvergedReason#

Gets the reason the KSP iteration was stopped.

Synopsis#

#include "petscksp.h" 
PetscErrorCode KSPGetConvergedReason(KSP ksp, KSPConvergedReason *reason)

Not Collective

Input Parameter#

  • ksp - the KSP context

Output Parameter#

  • reason - negative value indicates diverged, positive value converged, see KSPConvergedReason

Possible values for reason: See also manual page for each reason

   KSP_CONVERGED_RTOL (residual 2-norm decreased by a factor of rtol, from 2-norm of right hand side)
   KSP_CONVERGED_ATOL (residual 2-norm less than abstol)
   KSP_CONVERGED_ITS (used by the preonly preconditioner that always uses ONE iteration, or when the KSPConvergedSkip() convergence test routine is set.
   KSP_CONVERGED_CG_NEG_CURVE (see note below)
   KSP_CONVERGED_CG_CONSTRAINED (see note below)
   KSP_CONVERGED_STEP_LENGTH (see note below)
   KSP_CONVERGED_ITERATING (returned if the solver is not yet finished)
   KSP_DIVERGED_ITS  (required more than its to reach convergence)
   KSP_DIVERGED_DTOL (residual norm increased by a factor of divtol)
   KSP_DIVERGED_NANORINF (residual norm became Not-a-number or Inf likely due to 0/0)
   KSP_DIVERGED_BREAKDOWN (generic breakdown in method)
   KSP_DIVERGED_BREAKDOWN_BICG (Initial residual is orthogonal to preconditioned initial residual. Try a different preconditioner, or a different initial Level.)

Options Database Key#

  • -ksp_converged_reason - prints the reason to standard out

Notes#

If this routine is called before or doing the KSPSolve() the value of KSP_CONVERGED_ITERATING is returned

The values KSP_CONVERGED_CG_NEG_CURVE, KSP_CONVERGED_CG_CONSTRAINED, and KSP_CONVERGED_STEP_LENGTH are returned only by the special KSPNASH, KSPSTCG, and KSPGLTR solvers which are used by the SNESNEWTONTR (trust region) solver.

See Also#

KSP: Linear System Solvers, KSPConvergedReason, KSP, KSPSetConvergenceTest(), KSPConvergedDefault(), KSPSetTolerances(), KSPConvergedReason, KSPConvergedReasonView()

Level#

intermediate

Location#

src/ksp/ksp/interface/iterativ.c

Examples#

src/dm/impls/stag/tutorials/ex4.c.html
src/dm/impls/stag/tutorials/ex8.c.html
src/ksp/pc/tutorials/ex1.c.html
src/ksp/pc/tutorials/ex2.c.html
src/ksp/ksp/tutorials/ex59.c.html
src/ksp/ksp/tutorials/ex72.c.html
src/ksp/ksp/tutorials/ex77.c.html
src/snes/tutorials/ex6.c.html

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Index of all KSP routines
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Index of all manual pages