Implements the Pipelined (1-stage) Flexible Generalized Minimal Residual method. Pipelined Krylov Methods. Flexible Krylov Methods
Options Database Keys#
-the number of Krylov directions to orthogonalize against
-sets the tolerance for “happy ending” (exact convergence)
-ksp_gmres_preallocate - preallocate all the Krylov search directions initially (otherwise groups of
-ksp_pipefgmres_shift - the shift to use (defaults to 1. See KSPPIPEFGMRESSetShift() vectors are allocated as needed)
-ksp_gmres_krylov_monitor - plot the Krylov space generated
This variant is not “explicitly normalized” like
KSPPGMRES, and requires a shift parameter.
A heuristic for choosing the shift parameter is the largest eigenvalue of the preconditioned operator.
Only right preconditioning is supported (but this preconditioner may be nonlinear/variable/inexact, as with
MPI configuration may be necessary for reductions to make asynchronous progress, which is important for performance of pipelined methods. See What steps are necessary to make the pipelined solvers execute efficiently?
This class is subclassed off of
P. Sanan and S.M. Schnepp
P. Sanan, S.M. Schnepp, and D.A. May, “Pipelined, Flexible Krylov Subspace Methods,” SIAM Journal on Scientific Computing 2016 38:5, C441-C470, DOI: 10.1137/15M1049130
KSP: Linear System Solvers, What steps are necessary to make the pipelined solvers execute efficiently?, Pipelined Krylov Methods, Flexible Krylov Methods,
Index of all KSP routines
Table of Contents for all manual pages
Index of all manual pages