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# DMTSSetI2Function
set `TS` implicit function evaluation function for 2nd order systems 
## Synopsis
```
#include "petscts.h" 
PetscErrorCode DMTSSetI2Function(DM dm, TSI2Function fun, void *ctx)
```
Not Collective


## Input Parameters

- ***dm -*** `DM` to be used with `TS`
- ***fun -*** function evaluation routine
- ***ctx -*** context for residual evaluation



## Calling sequence of `fun`
```none
PetscErrorCode fun(TS ts, PetscReal t, Vec U, Vec U_t, Vec U_tt, Vec F,void *ctx);
```

- ***ts  -*** the `TS` context obtained from `TSCreate()`
- ***t    -*** time at step/stage being solved
- ***U    -*** state vector
- ***U_t  -*** time derivative of state vector
- ***U_tt -*** second time derivative of state vector
- ***F    -*** function vector
- ***ctx  -*** [optional] user-defined context for matrix evaluation routine (may be `NULL`)





## Note
`TSSetI2Function()` is normally used, but it calls this function internally because the user context is actually
associated with the `DM`.


## See Also
 [](ch_ts), `DM`, `TS`, `TSSetI2Function()`

## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ts/utils/dmts.c.html#DMTSSetI2Function">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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