SNESKSPSetUseEW

Sets SNES to the use Eisenstat-Walker method for computing relative tolerance for linear solvers within an inexact Newton method.

Synopsis

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

Logically Collective

Input Parameters

• snes - SNES context

• flag - PETSC_TRUE or PETSC_FALSE

Options Database Keys

• -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence

• -snes_ksp_ew_version ver - version of Eisenstat-Walker method

• -snes_ksp_ew_rtol0 rtol0 - Sets rtol0

• -snes_ksp_ew_rtolmax rtolmax - Sets rtolmax

• -snes_ksp_ew_gamma gamma - Sets gamma

• -snes_ksp_ew_alpha alpha - Sets alpha

• -snes_ksp_ew_alpha2 alpha2 - Sets alpha2

• -snes_ksp_ew_threshold threshold - Sets threshold

Note

The default is to use a constant relative tolerance for the inner linear solvers. Alternatively, one can use the Eisenstat-Walker method [EW96], where the relative convergence tolerance is reset at each Newton iteration according progress of the nonlinear solver.

References

[EW96]

S. C. Eisenstat and H. F. Walker. Choosing the forcing terms in an inexact Newton method. SIAM J. Scientific Computing, 17:16–32, 1996.

See Also

SNES: Nonlinear Solvers, KSP, SNES, SNESKSPGetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()

Level

advanced

Location

src/snes/interface/snes.c

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