KSPPGMRES#
Implements the Pipelined Generalized Minimal Residual method.
Options Database Keys#
-ksp_gmres_restart
- the number of Krylov directions to orthogonalize against-ksp_gmres_haptol
- sets the tolerance for “happy ending” (exact convergence)-ksp_gmres_preallocate - preallocate all the Krylov search directions initially (otherwise groups of vectors are allocated as needed)
-ksp_gmres_classicalgramschmidt - use classical (unmodified) Gram-Schmidt to orthogonalize against the Krylov space (fast) (the default)
-ksp_gmres_modifiedgramschmidt - use modified Gram-Schmidt in the orthogonalization (more stable, but slower)
-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.
-ksp_gmres_krylov_monitor - plot the Krylov space generated
Notes#
MPI configuration may be necessary for reductions to make asynchronous progress, which is important for performance of pipelined methods. See the FAQ on the PETSc website for details.
Reference#
Ghysels, Ashby, Meerbergen, Vanroose, Hiding global communication latencies in the GMRES algorithm on massively parallel machines, 2012.
Developer Notes#
This object is subclassed off of KSPGMRES
See Also#
KSPCreate()
, KSPSetType()
, KSPType
, KSP
, KSPGMRES
, KSPLGMRES
, KSPPIPECG
, KSPPIPECR
,
KSPGMRESSetRestart()
, KSPGMRESSetHapTol()
, KSPGMRESSetPreAllocateVectors()
, KSPGMRESSetOrthogonalization()
, KSPGMRESGetOrthogonalization()
,
KSPGMRESClassicalGramSchmidtOrthogonalization()
, KSPGMRESModifiedGramSchmidtOrthogonalization()
,
KSPGMRESCGSRefinementType
, KSPGMRESSetCGSRefinementType()
, KSPGMRESGetCGSRefinementType()
, KSPGMRESMonitorKrylov()
Level#
beginner
Location#
src/ksp/ksp/impls/gmres/pgmres/pgmres.c
Index of all KSP routines
Table of Contents for all manual pages
Index of all manual pages