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 n)
Collective
Input Parameters#
pc - the preconditioner context
n - number of its
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 Chebyshev with Jacobi (diagonal) preconditioning is used for smoothing, then the eigenvalue estimates can be reused during the solution process
This option is only used when the smoother uses Jacobi, and should be turned off if a different PCJacobiType
is used.
It became default in PETSc 3.17.
See Also#
PCGAMG
, KSPChebyshevSetEigenvalues()
, KSPChebyshevEstEigSet()
Level#
advanced
Location#
Implementations#
PCGAMGSetUseSAEstEig_GAMG in src/ksp/pc/impls/gamg/gamg.c
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