KSPPIPEFGMRESSetShift#
Set the shift parameter for the flexible, pipelined KSPPIPEFGMRES solver.
Synopsis#
#include "petscksp.h"
PetscErrorCode KSPPIPEFGMRESSetShift(KSP ksp, PetscScalar shift)
Logically Collective
Input Parameters#
ksp - the Krylov space context
shift - the shift
Options Database Key#
-ksp_pipefgmres_shift
- set the shift parameter
Note#
A heuristic is to set this to be comparable to the largest eigenvalue of the preconditioned operator.
This can be achieved with PETSc itself by using a few iterations of a Krylov method.
See KSPComputeEigenvalues() (and note the caveats there).
See Also#
KSP: Linear System Solvers, KSPPIPEFGMRES, KSPComputeEigenvalues()
Level#
intermediate
Location#
src/ksp/ksp/impls/gmres/pipefgmres/pipefgmres.c
Index of all KSP routines
Table of Contents for all manual pages
Index of all manual pages