KSPGMRESSetHapTol

Sets tolerance for determining happy breakdown in KSPGMRES, KSPFGMRES and KSPLGMRES

Synopsis

#include "petscksp.h"  
PetscErrorCode KSPGMRESSetHapTol(KSP ksp, PetscReal tol)

Logically Collective

Input Parameters

• ksp - the Krylov space context

• tol - the tolerance

Options Database Key

• -ksp_gmres_haptol - set tolerance for determining happy breakdown

Note

Happy breakdown is the rare case in KSPGMRES where an ‘exact’ solution is obtained after a certain number of iterations. If you attempt more iterations after this point unstable things can happen hence very occasionally you may need to set this value to detect this condition

See Also

KSP: Linear System Solvers, KSPGMRES, KSPSetTolerances()

Level

intermediate

Location

src/ksp/ksp/impls/gmres/gmres.c

Implementations

KSPGMRESSetHapTol_GMRES() in src/ksp/ksp/impls/gmres/gmres.c

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