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

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Index of all KSP routines
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