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# SNESNGSGetTolerances

Gets various parameters used in convergence tests for nonlinear Gauss-Seidel `SNESNCG`

## Synopsis

    #include "petscsnes.h"
    PetscErrorCode SNESNGSGetTolerances(SNES snes, PetscReal *atol, PetscReal *rtol, PetscReal *stol, PetscInt *maxit)

Not Collective

## Input Parameters

- snes - the `SNES` context

- atol - absolute convergence tolerance

- rtol - relative convergence tolerance

- stol - convergence tolerance in terms of the norm of the change in the solution between steps

- maxit - maximum number of iterations

## Note

The user can specify `NULL` for any parameter that is not needed.

## See Also

SNES: Nonlinear Solvers, `SNES`, `SNESNCG`, `SNESSetTolerances()`

## Level

intermediate

## Location

src/snes/impls/gs/snesgs.c

## Examples

src/snes/tutorials/ex5.c
src/snes/tutorials/ex19.c
src/snes/tutorials/ex15.c
src/snes/tutorials/ex55.c

Index of all SNES routines
Table of Contents for all manual pages
Index of all manual pages