KSPGMRES#
Implements the Generalized Minimal Residual method [SS86] with restart
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
Note#
Left and right preconditioning are supported, but not symmetric preconditioning.
References#
Y. Saad and M. Schultz. GMRES: A generalized minimal residual algorithm for solving nonsymmetric linear systems. SIAM Journal on Scientific and Statistical Computing, 44:856–869, 1986.
See Also#
KSP: Linear System Solvers, KSPCreate(), KSPSetType(), KSPType, KSP, KSPFGMRES, KSPLGMRES,
KSPGMRESSetRestart(), KSPGMRESSetHapTol(), KSPGMRESSetPreAllocateVectors(), KSPGMRESSetOrthogonalization(), KSPGMRESGetOrthogonalization(),
KSPGMRESClassicalGramSchmidtOrthogonalization(), KSPGMRESModifiedGramSchmidtOrthogonalization(),
KSPGMRESCGSRefinementType, KSPGMRESSetCGSRefinementType(), KSPGMRESGetCGSRefinementType(), KSPGMRESMonitorKrylov(), KSPSetPCSide()
Level#
beginner
Location#
Examples#
src/tao/pde_constrained/tutorials/hyperbolic.c
src/ksp/ksp/tutorials/ex7.c
src/ksp/ksp/tutorials/ex8.c
src/ksp/ksp/tutorials/ex62.c
Index of all KSP routines
Table of Contents for all manual pages
Index of all manual pages