# DMComputeError
Computes the error assuming the user has provided the exact solution functions 
## Synopsis
```
#include "petscdm.h"          
#include "petscdmlabel.h"     
#include "petscds.h"     
PetscErrorCode DMComputeError(DM dm, Vec sol, PetscReal errors[], Vec *errorVec)
```
Collective on dm


## Input Parameters

- ***dm     -*** The `DM`
- ***sol    -*** The solution vector



## Input/Output Parameter

- ***errors -*** An array of length Nf, the number of fields, or NULL for no output; on output
contains the error in each field



## Output Parameter

- ***errorVec -*** A vector to hold the cellwise error (may be NULL)



## Note
The exact solutions come from the `PetscDS` object, and the time comes from `DMGetOutputSequenceNumber()`.




## See Also
 `DMMonitorSet()`, `DMGetRegionNumDS()`, `PetscDSGetExactSolution()`, `DMGetOutputSequenceNumber()`

## Level
developer

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


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[Index of all DM routines](index.md)  
[Table of Contents for all manual pages](/docs/manualpages/index.md)  
[Index of all manual pages](/docs/manualpages/singleindex.md)  
