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# DMSwarmInitializeVelocities
Set the initial velocities of particles using a distribution. 
## Synopsis
```
#include "petscdmswarm.h"   
PetscErrorCode DMSwarmInitializeVelocities(DM sw, PetscProbFunc sampler, const PetscReal v0[])
```
Collective


## Input Parameters

- ***sw      -*** The `DMSWARM` object
- ***sampler -*** A function which uniformly samples the velocity PDF
- ***v0      -*** The velocity scale for nondimensionalization for each species





## Note
If `v0` is zero for the first species, all velocities are set to zero. If it is zero for any other species, the effect will be to give that species zero velocity.


## See Also
 `DMSWARM`, `DMSwarmComputeLocalSize()`, `DMSwarmInitializeCoordinates()`, `DMSwarmInitializeVelocitiesFromOptions()`

## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/swarm/swarmpic.c.html#DMSwarmInitializeVelocities">src/dm/impls/swarm/swarmpic.c</A>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/dm/impls/swarm/swarmpic.c)


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