:orphan:
# TaoSetObjectiveAndGradient
Sets a combined objective function and gradient evaluation routine for the function to be optimized 
## Synopsis
```
#include "petsctao.h" 
PetscErrorCode TaoSetObjectiveAndGradient(Tao tao, Vec g, PetscErrorCode (*func)(Tao, Vec, PetscReal *, Vec, void *), void *ctx)
```
Logically Collective


## Input Parameters

- ***tao -*** the `Tao` context
- ***g -*** [optional] the vector to internally hold the gradient computation
- ***func -*** the gradient function
- ***ctx -*** [optional] user-defined context for private data for the gradient evaluation
routine (may be `NULL`)



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

- ***tao -*** the optimization object
- ***x -*** input vector
- ***f -*** objective value (output)
- ***g -*** gradient value (output)
- ***ctx -*** [optional] user-defined function context





## Note
For some optimization methods using a combined function can be more eifficient.


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

## Level
beginner

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

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/bound/tutorials/jbearing2.c.html">src/tao/bound/tutorials/jbearing2.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/bound/tutorials/plate2.c.html">src/tao/bound/tutorials/plate2.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/bound/tutorials/plate2f.F90.html">src/tao/bound/tutorials/plate2f.F90</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/constrained/tutorials/ex1.c.html">src/tao/constrained/tutorials/ex1.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/constrained/tutorials/maros.c.html">src/tao/constrained/tutorials/maros.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/constrained/tutorials/tomographyADMM.c.html">src/tao/constrained/tutorials/tomographyADMM.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/tutorials/ex3.c.html">src/tao/tutorials/ex3.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/unconstrained/tutorials/burgers_spectral.c.html">src/tao/unconstrained/tutorials/burgers_spectral.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/unconstrained/tutorials/eptorsion1.c.html">src/tao/unconstrained/tutorials/eptorsion1.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/unconstrained/tutorials/eptorsion2.c.html">src/tao/unconstrained/tutorials/eptorsion2.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/unconstrained/tutorials/eptorsion2f.F90.html">src/tao/unconstrained/tutorials/eptorsion2f.F90</A><BR>


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


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