:orphan:
# SNESApplyNPC
Calls `SNESSolve()` on preconditioner for the `SNES` 
## Synopsis
```
#include "petscsnes.h"  
PetscErrorCode SNESApplyNPC(SNES snes, Vec x, Vec f, Vec y)
```
Collective


## Input Parameters

- ***snes -*** the `SNES` context
- ***x -*** input vector
- ***f -*** optional; the function evaluation on `x`



## Output Parameter

- ***y -*** function vector, as set by `SNESSetFunction()`





## Note
`SNESComputeFunction()` should be called on `x` before `SNESApplyNPC()` is called, as it is
with `SNESComuteJacobian()`.


## See Also
 `SNESGetNPC()`, `SNESSetNPC()`, `SNESComputeFunction()`

## Level
developer

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/snes/interface/snespc.c.html#SNESApplyNPC">src/snes/interface/snespc.c</A>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/snes/interface/snespc.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)