petsc-3.5.4 2015-05-23

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 "petscksp.h" 
PetscErrorCode  PCApplyRichardson(PC pc,Vec b,Vec y,Vec w,PetscReal rtol,PetscReal abstol, PetscReal dtol,PetscInt its,PetscBool guesszero,PetscInt *outits,PCRichardsonConvergedReason *reason)

Collective on PC

Input Parameters

	pc	- the preconditioner context
	b	- the right hand side
	w	- one work vector
	rtol	- relative decrease in residual norm convergence criteria
	abstol	- absolute residual norm convergence criteria
	dtol	- divergence residual norm increase criteria
	its	- the number of iterations to apply.
	guesszero	- if the input x contains nonzero initial guess

Output Parameter

	outits	- number of iterations actually used (for SOR this always equals its)
	reason	- the reason the apply terminated
	y	- the solution (also contains initial guess if guesszero is PETSC_FALSE

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