# MatNullSpaceCreateRigidBody
create rigid body modes from coordinates 
## Synopsis
```
#include "petscmat.h" 
PetscErrorCode MatNullSpaceCreateRigidBody(Vec coords, MatNullSpace *sp)
```
Collective on coords


## Input Parameter

- ***coords -*** block of coordinates of each node, must have block size set



## Output Parameter

- ***sp -*** the null space





## Notes
If you are solving an elasticity problem you should likely use this, in conjunction with `MatSetNearNullSpace()`, to provide information that
the `PCGAMG` preconditioner can use to construct a much more efficient preconditioner.

If you are solving an elasticity problem with pure Neumann boundary conditions you can use this in conjunction with `MatSetNullSpace()` to
provide this information to the linear solver so it can handle the null space appropriately in the linear solution.


## See Also
 `MatNullSpace`, `MatNullSpaceCreate()`, `MatSetNearNullSpace()`, `MatSetNullSpace()`

## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/interface/matnull.c.html#MatNullSpaceCreateRigidBody">src/mat/interface/matnull.c</A>

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/ex49.c.html">src/ksp/ksp/tutorials/ex49.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/ex56.c.html">src/ksp/ksp/tutorials/ex56.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/ex71.c.html">src/ksp/ksp/tutorials/ex71.c.html</A><BR>


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