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# TaoSetJacobianRoutine
Sets the function to compute the Jacobian as well as the location to store the matrix. 
## Synopsis
```
#include "petsctao.h" 
PetscErrorCode TaoSetJacobianRoutine(Tao tao, Mat J, Mat Jpre, PetscErrorCode (*func)(Tao, Vec, Mat, Mat, void *), void *ctx)
```
Logically Collective


## Input Parameters

- ***tao  -*** the `Tao` context
- ***J    -*** Matrix used for the Jacobian
- ***Jpre -*** Matrix that will be used to construct the preconditioner, can be same as `J`
- ***func -*** Jacobian evaluation routine
- ***ctx  -*** [optional] user-defined context for private data for the
Jacobian evaluation routine (may be `NULL`)



## Calling sequence of `func`
```none
PetscErrorCode func(Tao tao, Vec x, Mat J, Mat Jpre, void *ctx);
```

- ***tao  -*** the `Tao` context
- ***x    -*** input vector
- ***J    -*** Jacobian matrix
- ***Jpre -*** matrix used to construct the preconditioner, usually the same as `J`
- ***ctx  -*** [optional] user-defined Jacobian context





## See Also
 [](ch_tao), `Tao`, `TaoSetGradient()`, `TaoSetObjective()`

## Level
intermediate

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/interface/taosolver_hj.c.html#TaoSetJacobianRoutine">src/tao/interface/taosolver_hj.c</A>

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/complementarity/tutorials/blackscholes.c.html">src/tao/complementarity/tutorials/blackscholes.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/complementarity/tutorials/minsurf1.c.html">src/tao/complementarity/tutorials/minsurf1.c</A><BR>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/tao/interface/taosolver_hj.c)


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