PCGAMGSetUseSAEstEig#
Use the eigen estimate from smoothed aggregation for the Chebyshev smoother during the solution process
Synopsis#
#include "petscpc.h"
#include "petscksp.h"
PetscErrorCode PCGAMGSetUseSAEstEig(PC pc, PetscBool b)
Collective
Input Parameters#
pc - the preconditioner context
b - flag
Options Database Key#
-pc_gamg_use_sa_esteig <true,false> - use the eigen estimate
Notes#
Smoothed aggregation constructs the smoothed prolongator \(P = (I - \omega D^{-1} A) T\) where \(T\) is the tentative prolongator and \(D\) is the diagonal of \(A\).
Eigenvalue estimates (based on a few PCCG
or PCGMRES
iterations) are computed to choose \(\omega\) so that this is a stable smoothing operation.
If KSPCHEBYSHEV
with PCJACOBI
(diagonal) preconditioning is used for smoothing on the finest level, then the eigenvalue estimates
can be reused during the solution process.
This option is only used when the smoother uses PCJACOBI
, and should be turned off when a different PCJacobiType
is used.
It became default in PETSc 3.17.
See Also#
the Users Manual section on PCGAMG, the Users Manual section on PCMG, KSP: Linear System Solvers, PCGAMG
, KSPChebyshevSetEigenvalues()
, KSPChebyshevEstEigSet()
, PCGAMGSetRecomputeEstEig()
Level#
advanced
Location#
Examples#
Implementations#
PCGAMGSetUseSAEstEig_GAMG() in src/ksp/pc/impls/gamg/gamg.c
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