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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
 `SNESNCG`, `SNESSetTolerances()`

## Level
intermediate

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/snes/impls/gs/snesgs.c.html#SNESNGSGetTolerances">src/snes/impls/gs/snesgs.c</A>

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/snes/tutorials/ex15.c.html">src/snes/tutorials/ex15.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/snes/tutorials/ex16.c.html">src/snes/tutorials/ex16.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/snes/tutorials/ex19.c.html">src/snes/tutorials/ex19.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/snes/tutorials/ex5.c.html">src/snes/tutorials/ex5.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/snes/tutorials/ex55.c.html">src/snes/tutorials/ex55.c</A><BR>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/snes/impls/gs/snesgs.c)


[Index of all SNES routines](index.md)  
[Table of Contents for all manual pages](/manualpages/index.md)  
[Index of all manual pages](/manualpages/singleindex.md)  
