:orphan:
# PetscDSSetObjective
Set the pointwise objective function for a given test field 
## Synopsis
```
#include "petscds.h" 
PetscErrorCode PetscDSSetObjective(PetscDS ds, PetscInt f, void (*obj)(PetscInt dim, PetscInt Nf, PetscInt NfAux, const PetscInt uOff[], const PetscInt uOff_x[], const PetscScalar u[], const PetscScalar u_t[], const PetscScalar u_x[], const PetscInt aOff[], const PetscInt aOff_x[], const PetscScalar a[], const PetscScalar a_t[], const PetscScalar a_x[], PetscReal t, const PetscReal x[], PetscInt numConstants, const PetscScalar constants[], PetscScalar obj[]))
```
Not Collective


## Input Parameters

- ***ds  -*** The `PetscDS`
- ***f   -*** The test field number
- ***obj -*** integrand for the test function term



## Calling sequence of `obj`
```none
  void f0(PetscInt dim, PetscInt Nf, PetscInt NfAux,
          const PetscInt uOff[], const PetscInt uOff_x[], const PetscScalar u[], const PetscScalar u_t[], const PetscScalar u_x[],
          const PetscInt aOff[], const PetscInt aOff_x[], const PetscScalar a[], const PetscScalar a_t[], const PetscScalar a_x[],
          PetscReal t, const PetscReal x[], PetscInt numConstants, const PetscScalar constants[], PetscScalar obj[])
```


- ***dim -*** the spatial dimension
- ***Nf -*** the number of fields
- ***uOff -*** the offset into u[] and u_t[] for each field
- ***uOff_x -*** the offset into u_x[] for each field
- ***u -*** each field evaluated at the current point
- ***u_t -*** the time derivative of each field evaluated at the current point
- ***u_x -*** the gradient of each field evaluated at the current point
- ***aOff -*** the offset into a[] and a_t[] for each auxiliary field
- ***aOff_x -*** the offset into a_x[] for each auxiliary field
- ***a -*** each auxiliary field evaluated at the current point
- ***a_t -*** the time derivative of each auxiliary field evaluated at the current point
- ***a_x -*** the gradient of auxiliary each field evaluated at the current point
- ***t -*** current time
- ***x -*** coordinates of the current point
- ***numConstants -*** number of constant parameters
- ***constants -*** constant parameters
- ***obj -*** output values at the current point





## Note
We are using a first order FEM model for the weak form:  \int_\Omega \phi obj(u, u_t, \nabla u, x, t)


## See Also
 `PetscDS`, `PetscDSGetObjective()`, `PetscDSSetResidual()`

## Level
intermediate

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/dt/interface/dtds.c.html#PetscDSSetObjective">src/dm/dt/interface/dtds.c</A>

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/snes/tutorials/ex13.c.html">src/snes/tutorials/ex13.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/snes/tutorials/ex69.c.html">src/snes/tutorials/ex69.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ts/tutorials/ex48.c.html">src/ts/tutorials/ex48.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ts/utils/dmplexlandau/tutorials/ex1.c.html">src/ts/utils/dmplexlandau/tutorials/ex1.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ts/utils/dmplexlandau/tutorials/ex2.c.html">src/ts/utils/dmplexlandau/tutorials/ex2.c</A><BR>


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


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