petsc-3.4.5 2014-06-29

SNESKSPGetUseEW

Gets if SNES is using Eisenstat-Walker method for computing relative tolerance for linear solvers within an inexact Newton method.

Synopsis

#include "petscsnes.h"  
PetscErrorCode  SNESKSPGetUseEW(SNES snes, PetscBool  *flag)

Not Collective

Input Parameter

snes -SNES context

Output Parameter

flag -PETSC_TRUE or PETSC_FALSE

Notes

Currently, the default is to use a constant relative tolerance for the inner linear solvers. Alternatively, one can use the Eisenstat-Walker method, where the relative convergence tolerance is reset at each Newton iteration according progress of the nonlinear solver.

Reference

S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an inexact Newton method", SISC 17 (1), pp.16-32, 1996.

Keywords

SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton