PCApplyRichardson

Applies several steps of Richardson iteration with the particular preconditioner. This routine is usually used by the Krylov solvers and not the application code directly.

Synopsis

#include "petscsles.h" 
int PCApplyRichardson(PC pc,Vec x,Vec y,Vec w,PetscReal rtol,PetscReal atol, PetscReal dtol,int its)

Collective on PC

Input Parameters

	pc	- the preconditioner context
	x	- the initial guess
	w	- one work vector
	rtol	- relative decrease in residual norm convergence criteria
	atol	- absolute residual norm convergence criteria
	dtol	- divergence residual norm increase criteria
	its	- the number of iterations to apply.

Output Parameter

y -the solution

Notes

Most preconditioners do not support this function. Use the command PCApplyRichardsonExists() to determine if one does.

Except for the multigrid PC this routine ignores the convergence tolerances and always runs for the number of iterations

Keywords