petsc-3.7.5 2017-01-01

PCEisenstatGetNoDiagonalScaling

Tells if the Eisenstat preconditioner not to do additional diagonal preconditioning. For matrices with a constant along the diagonal, this may save a small amount of work.

Synopsis

#include "petscpc.h" 
PetscErrorCode  PCEisenstatGetNoDiagonalScaling(PC pc,PetscBool *flg)

Logically Collective on PC

Input Parameter

pc -the preconditioner context

Output Parameter

flg -PETSC_TRUE means there is no diagonal scaling applied

Options Database Key

-pc_eisenstat_no_diagonal_scaling -Activates PCEisenstatSetNoDiagonalScaling()

Note

If you use the KPSSetDiagonalScaling() or -ksp_diagonal_scale option then you will likley want to use this routine since it will save you some unneeded flops.

Keywords

PC, Eisenstat, use, diagonal, scaling, SSOR