KSPGMRESSetOrthogonalization

Sets the orthogonalization routine used by GMRES.

Synopsis

int KSPGMRESSetOrthogonalization( KSP ksp,int (*fcn)(KSP,int) )
Collective on KSP

Input Parameters

ksp - iterative context obtained from KSPCreate
fcn - Orthogonalization function

Notes

Several orthogonalization routines are predefined.

KSPGMRESModifiedGramSchmidtOrthogonalization() - default.

KSPGMRESUnmodifiedGramSchmidtOrthogonalization() - NOT recommended; however, for some problems, particularlywhen using parallel distributed vectors, this may besignificantly faster.

KSPGMRESIROrthogonalization() - iterative refinementversion of KSPGMRESUnmodifiedGramSchmidtOrthogonalization(), which may be more numerically stable.

Options Database Keys

-ksp_gmres_unmodifiedgramschmidt -Activates KSPGMRESUnmodifiedGramSchmidtOrthogonalization()
-ksp_gmres_irorthog -Activates KSPGMRESIROrthogonalization()

Keywords

GMRES, set, orthogonalization, Gram-Schmidt, iterative refinement

See Also

KSPGMRESSetRestart(), KSPGMRESSetPreallocateVectors()

Location: src/ksp/impls/gmres/gmres2.c
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