petsc-3.14.6 2021-03-30

KSPGMRESGetOrthogonalization

Gets the orthogonalization routine used by GMRES and FGMRES.

#include "petscksp.h"  
PetscErrorCode  KSPGMRESGetOrthogonalization(KSP ksp,PetscErrorCode (**fcn)(KSP,PetscInt))

Not Collective

ksp

- iterative context obtained from KSPCreate

fcn

- orthogonalization function

  errorcode = PetscErrorCode fcn(KSP ksp,PetscInt it);

  it is one minus the number of GMRES iterations since last restart;

   i.e. the size of Krylov space minus one

Two orthogonalization routines are predefined, including

KSPGMRESClassicalGramSchmidtOrthogonalization() - Default. Use KSPGMRESSetCGSRefinementType() to determine if iterative refinement is used to increase stability.

	-ksp_gmres_classicalgramschmidt	- Activates KSPGMRESClassicalGramSchmidtOrthogonalization() (default)
	-ksp_gmres_modifiedgramschmidt	- Activates KSPGMRESModifiedGramSchmidtOrthogonalization()

intermediate