SNESConvergedDefault#

Default onvergence test of the solvers for systems of nonlinear equations.

Synopsis#

#include "petsc/private/snesimpl.h"   
PetscErrorCode SNESConvergedDefault(SNES snes, PetscInt it, PetscReal xnorm, PetscReal snorm, PetscReal fnorm, SNESConvergedReason *reason, void *dummy)

Collective

Input Parameters#

snes - the SNES context
it - the iteration (0 indicates before any Newton steps)
xnorm - 2-norm of current iterate
snorm - 2-norm of current step
fnorm - 2-norm of function at current iterate
dummy - unused context

Output Parameter#

reason - one of

   SNES_CONVERGED_FNORM_ABS       - (fnorm < abstol),
   SNES_CONVERGED_SNORM_RELATIVE  - (snorm < stol*xnorm),
   SNES_CONVERGED_FNORM_RELATIVE  - (fnorm < rtol*fnorm0),
   SNES_DIVERGED_FUNCTION_COUNT   - (nfct > maxf),
   SNES_DIVERGED_FNORM_NAN        - (fnorm == NaN),
   SNES_CONVERGED_ITERATING       - (otherwise),
   SNES_DIVERGED_DTOL             - (fnorm > divtol*snes->fnorm0)

where

maxf - maximum number of function evaluations, set with SNESSetTolerances()
nfct - number of function evaluations,
abstol - absolute function norm tolerance, set with SNESSetTolerances()
rtol - relative function norm tolerance, set with SNESSetTolerances()
divtol - divergence tolerance, set with SNESSetDivergenceTolerance()
fnorm0 - 2-norm of the function at the initial solution (initial guess; zeroth iteration)

Options Database Keys#

-snes_convergence_test default - see SNESSetFromOptions()
-snes_stol - convergence tolerance in terms of the norm of the change in the solution between steps
-snes_atol - absolute tolerance of residual norm
-snes_rtol - relative decrease in tolerance norm from the initial 2-norm of the solution
-snes_divergence_tolerance - if the residual goes above divtol*rnorm0, exit with divergence
-snes_max_funcs <max_funcs> - maximum number of function evaluations
-snes_max_fail <max_fail> - maximum number of line search failures allowed before stopping, default is none
-snes_max_linear_solve_fail - number of linear solver failures before SNESSolve() stops