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# TaoSetObjective
Sets the function evaluation routine for minimization 
## Synopsis
```
#include "petsctao.h" 
PetscErrorCode TaoSetObjective(Tao tao, PetscErrorCode (*func)(Tao, Vec, PetscReal *, void *), void *ctx)
```
Logically Collective


## Input Parameters

- ***tao -*** the `Tao` context
- ***func -*** the objective function
- ***ctx -*** [optional] user-defined context for private data for the function evaluation
routine (may be `NULL`)



## Calling sequence of `func`
```none
PetscErrorCode func(Tao tao, Vec x, PetscReal *f, void *ctx);
```

- ***tao -*** the optimizer
- ***x -*** input vector
- ***f -*** function value
- ***ctx -*** [optional] user-defined function context





## See Also
 [](ch_tao), `TaoSetGradient()`, `TaoSetHessian()`, `TaoSetObjectiveAndGradient()`, `TaoGetObjective()`

## Level
beginner

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

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/pde_constrained/tutorials/elliptic.c.html">src/tao/pde_constrained/tutorials/elliptic.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/pde_constrained/tutorials/hyperbolic.c.html">src/tao/pde_constrained/tutorials/hyperbolic.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/pde_constrained/tutorials/parabolic.c.html">src/tao/pde_constrained/tutorials/parabolic.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/tutorials/ex4.c.html">src/tao/tutorials/ex4.c</A><BR>


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


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