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