KSPLGMRES#
Augments the standard GMRES approximation space with approximations to the error from previous restart cycles.
Options Database Keys#
- -ksp_gmres_restart
total approximation space size (Krylov directions + error approximations)
- -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
- -ksp_lgmres_augment
number of error approximations to augment the Krylov space with
- -ksp_lgmres_constant
use a constant approx. space size (only affects restart cycles < num. error approx.(k), i.e. the first k restarts)
To run LGMRES(m, k) as described in the above paper, use#
-ksp_gmres_restart <m+k>
-ksp_lgmres_augment
Notes#
Supports both left and right preconditioning, but not symmetric.
References#
: A. H. Baker, E.R. Jessup, and T.A. Manteuffel. A technique for accelerating the convergence of restarted GMRES. SIAM Journal on Matrix Analysis and Applications, 26 (2005).
Developer Notes#
This object is subclassed off of KSPGMRES
Contributed by: Allison Baker
See Also#
KSPCreate(), KSPSetType(), KSPType, KSP, KSPFGMRES, KSPGMRES,
KSPGMRESSetRestart(), KSPGMRESSetHapTol(), KSPGMRESSetPreAllocateVectors(), KSPGMRESSetOrthogonalization(), KSPGMRESGetOrthogonalization(),
KSPGMRESClassicalGramSchmidtOrthogonalization(), KSPGMRESModifiedGramSchmidtOrthogonalization(),
KSPGMRESCGSRefinementType, KSPGMRESSetCGSRefinementType(), KSPGMRESGetCGSRefinementType(), KSPGMRESMonitorKrylov(), KSPLGMRESSetAugDim(),
KSPGMRESSetConstant()
Level#
beginner
Location#
src/ksp/ksp/impls/gmres/lgmres/lgmres.c
Index of all KSP routines
Table of Contents for all manual pages
Index of all manual pages