:orphan:
# SNESSetInitialFunction
Sets the function vector to be used as the initial function value at the initialization of the method.  In some instances, the user has precomputed the function before calling `SNESSolve()`.  This function allows one to avoid a redundant call to `SNESComputeFunction()` in that case. 
## Synopsis
```
#include "petscsnes.h"  
PetscErrorCode SNESSetInitialFunction(SNES snes, Vec f)
```
Logically Collective


## Input Parameters

- ***snes -*** the `SNES` context
- ***f -*** vector to store function value





## Notes
This should not be modified during the solution procedure.

This is used extensively in the `SNESFAS` hierarchy and in nonlinear preconditioning.


## See Also
 [](ch_snes), `SNES`, `SNESFAS`, `SNESSetFunction()`, `SNESComputeFunction()`, `SNESSetInitialFunctionNorm()`

## Level
developer

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