# DMTSSetIFunction
set TS implicit function evaluation function 
## Synopsis
```
#include "petscts.h" 
PetscErrorCode DMTSSetIFunction(DM dm, TSIFunction func, void *ctx)
```
Not Collective


## Input Parameters

- ***dm -*** DM to be used with TS
- ***func -*** function evaluating f(t,u,u_t)
- ***ctx -*** context for residual evaluation



## Calling sequence of func
```none
PetscErrorCode func(TS ts,PetscReal t,Vec u,Vec u_t,Vec F,ctx);
```


- ***t   -*** time at step/stage being solved
- ***u   -*** state vector
- ***u_t -*** time derivative of state vector
- ***F   -*** function vector
- ***ctx -*** [optional] user-defined context for matrix evaluation routine





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

## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ts/utils/dmts.c.html#DMTSSetIFunction">src/ts/utils/dmts.c</A>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/ts/utils/dmts.c)


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