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# PetscDSSetExactSolution
Set the pointwise exact solution function for a given test field
## Synopsis
```
#include "petscds.h"
PetscErrorCode PetscDSSetExactSolution(PetscDS prob, PetscInt f, PetscErrorCode (*sol)(PetscInt dim, PetscReal t, const PetscReal x[], PetscInt Nc, PetscScalar u[], void *ctx), void *ctx)
```
Not Collective
## Input Parameters
- ***prob -*** The `PetscDS`
- ***f -*** The test field number
- ***sol -*** solution function for the test fields
- ***ctx -*** solution context or `NULL`
## Calling sequence of `sol`
```none
PetscErrorCode sol(PetscInt dim, PetscReal t, const PetscReal x[], PetscInt Nc, PetscScalar u[], void *ctx)
```
- ***dim -*** the spatial dimension
- ***t -*** current time
- ***x -*** coordinates of the current point
- ***Nc -*** the number of field components
- ***u -*** the solution field evaluated at the current point
- ***ctx -*** a user context
## See Also
`PetscDS`, `PetscDSGetExactSolution()`
## Level
intermediate
## Location
src/dm/dt/interface/dtds.c
## Examples
src/snes/tutorials/ex12.c
src/snes/tutorials/ex13.c
src/snes/tutorials/ex17.c
src/snes/tutorials/ex20.c
src/snes/tutorials/ex23.c
src/snes/tutorials/ex24.c
src/snes/tutorials/ex26.c
src/snes/tutorials/ex36.c
src/snes/tutorials/ex62.c
src/snes/tutorials/ex69.c
src/snes/tutorials/ex71.c
---
[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/dm/dt/interface/dtds.c)
[Index of all DT routines](index.md)
[Table of Contents for all manual pages](/manualpages/index.md)
[Index of all manual pages](/manualpages/singleindex.md)