KSPGMRESClassicalGramSchmidtOrthogonalization#
This is the basic orthogonalization routine using classical Gram-Schmidt with possible iterative refinement to improve the stability
Synopsis#
Collective on ksp
Input Parameters#
ksp - KSP object, must be associated with GMRES, FGMRES, or LGMRES Krylov method
its - one less then the current GMRES restart iteration, i.e. the size of the Krylov space
Options Database Keys#
-ksp_gmres_classicalgramschmidt - Activates
KSPGMRESClassicalGramSchmidtOrthogonalization()
-ksp_gmres_cgs_refinement_type <refine_never,refine_ifneeded,refine_always> - determine if iterative refinement is used to increase the stability of the classical Gram-Schmidt orthogonalization.
Notes#
Use KSPGMRESSetCGSRefinementType()
to determine if iterative refinement is to be used.
This is much faster than KSPGMRESModifiedGramSchmidtOrthogonalization()
but has the small possibility of stability issues
that can usually be handled by using a a single step of iterative refinement with KSPGMRESSetCGSRefinementType()
See Also#
KSPGMRESSetOrthogonalization()
, KSPGMRESSetCGSRefinementType()
,
KSPGMRESGetCGSRefinementType()
, KSPGMRESGetOrthogonalization()
, KSPGMRESModifiedGramSchmidtOrthogonalization()
Level#
intermediate
Location#
Examples#
src/ksp/ksp/tutorials/ex5f.F90.html
Index of all KSP routines
Table of Contents for all manual pages
Index of all manual pages