petsc-3.14.5 2021-03-03
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# KSPGMRESModifiedGramSchmidtOrthogonalization

This is the basic orthogonalization routine using modified Gram-Schmidt.

### Synopsis

    PetscErrorCode  KSPGMRESModifiedGramSchmidtOrthogonalization(KSP ksp,PetscInt it)

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_modifiedgramschmidt | - Activates KSPGMRESModifiedGramSchmidtOrthogonalization()

### Notes

In general this is much slower than KSPGMRESClassicalGramSchmidtOrthogonalization() but has better stability properties.

### See Also

KSPGMRESSetOrthogonalization(), KSPGMRESClassicalGramSchmidtOrthogonalization(), KSPGMRESGetOrthogonalization()

### Level

intermediate

### Location

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

### 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