KSPChebyshevSetEigenvalues#
Sets estimates for the extreme eigenvalues of the preconditioned problem.
Synopsis#
#include "petscksp.h"
PetscErrorCode KSPChebyshevSetEigenvalues(KSP ksp, PetscReal emax, PetscReal emin)
Logically Collective
Input Parameters#
ksp - the Krylov space context
emax - the eigenvalue maximum estimate
emin - the eigenvalue minimum estimate
Options Database Key#
-ksp_chebyshev_eigenvalues emin,emax - extreme eigenvalues
Notes#
Call KSPChebyshevEstEigSet() or use the option -ksp_chebyshev_esteig a,b,c,d to have the KSP
estimate the eigenvalues and use these estimated values automatically.
When KSPCHEBYSHEV is used as a smoother, one often wants to target a portion of the spectrum rather than the entire
spectrum. This function takes the range of target eigenvalues for Chebyshev, which will often slightly over-estimate
the largest eigenvalue of the actual operator (for safety) and greatly overestimate the smallest eigenvalue to
improve the smoothing properties of Chebyshev iteration on the higher frequencies in the spectrum.
See Also#
KSP: Linear System Solvers, KSPCHEBYSHEV, KSPChebyshevEstEigSet(),
Level#
intermediate
Location#
Implementations#
KSPChebyshevSetEigenvalues_Chebyshev() in src/ksp/ksp/impls/cheby/cheby.c
Index of all KSP routines
Table of Contents for all manual pages
Index of all manual pages