petsc-3.12.1 2019-10-22
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# KSP_GMRES_CGS_REFINE_NEVER

Do two steps of the classical (unmodified) Gram-Schmidt process.

Note: This is roughly twice the cost of KSP_GMRES_CGS_REFINE_NEVER because it performs the process twice but it saves the extra norm calculation needed by KSP_GMRES_CGS_REFINE_IFNEEDED.

You should only use this if you absolutely know that the iterative refinement is needed.

### See Also

KSPGMRESClassicalGramSchmidtOrthogonalization(), KSPGMRESSetOrthogonalization(), KSPGMRESGetOrthogonalization(),
KSPGMRESSetCGSRefinementType(), KSPGMRESGetCGSRefinementType(), KSP_GMRES_CGS_REFINE_IFNEEDED, KSP_GMRES_CGS_REFINE_ALWAYS, KSPGMRESModifiedGramSchmidtOrthogonalization()

### Level

advanced

### Location

src/ksp/ksp/guess/../../../../include/petscksp.h
Index of all KSP routines
Table of Contents for all manual pages
Index of all manual pages