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# DMSNESGetNGS
get `SNES` Gauss-Seidel relaxation function 
## Synopsis
```
#include "petscsnes.h" 
#include "petscdm.h" 
PetscErrorCode DMSNESGetNGS(DM dm, PetscErrorCode (**f)(SNES, Vec, Vec, void *), void **ctx)
```
Not Collective


## Input Parameter

- ***dm -*** `DM` to be used with `SNES`



## Output Parameters

- ***f -*** relaxation function which performs Gauss-Seidel sweeps, see `SNESSetNGS()`
- ***ctx -*** context for residual evaluation





## Note
`SNESGetNGS()` is normally used, but it calls this function internally because the user context is actually
associated with the `DM`.


## Developer Note
This makes the interface consistent regardless of whether the user interacts with a `DM` or
not. If `DM` took a more central role at some later date, this could become the primary method of setting the residual.


## See Also
 `DMSNESSetContext()`, `SNESGetNGS()`, `DMSNESGetJacobian()`, `DMSNESGetFunction()`

## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/snes/utils/dmsnes.c.html#DMSNESGetNGS">src/snes/utils/dmsnes.c</A>


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[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)