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

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 KSPSetDiagonalScaling() or -ksp_diagonal_scale option then you will likely want to use this routine since it will save you some unneeded flops.