:orphan:
# DMGetDefaultConstraints
Get the `PetscSection` and `Mat` that specify the local constraint interpolation. See `DMSetDefaultConstraints()` for a description of the purpose of constraint interpolation. 
## Synopsis
```
#include "petscdm.h"          
#include "petscdmlabel.h"     
#include "petscds.h"     
PetscErrorCode DMGetDefaultConstraints(DM dm, PetscSection *section, Mat *mat, Vec *bias)
```
not Collective


## Input Parameter

- ***dm -*** The `DM`



## Output Parameters

- ***section -*** The `PetscSection` describing the range of the constraint matrix: relates rows of the constraint matrix to dofs of the default section.  Returns `NULL` if there are no local constraints.
- ***mat -*** The `Mat` that interpolates local constraints: its width should be the layout size of the default section.  Returns `NULL` if there are no local constraints.
- ***bias -*** Vector containing bias to be added to constrained dofs





## Note
This gets borrowed references, so the user should not destroy the `PetscSection`, `Mat`, or `Vec`.


## See Also
 [](ch_dmbase), `DM`, `DMSetDefaultConstraints()`

## Level
advanced

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


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