# DMSwarmVectorDefineField
Sets the field from which to define a Vec object when DMCreateLocalVector(), or DMCreateGlobalVector() is called 
## Synopsis
```
#include "petscdmswarm.h"   
PetscErrorCode DMSwarmVectorDefineField(DM dm, const char fieldname[])
```
Collective on dm


## Input parameters

- ***dm -*** a DMSwarm
- ***fieldname -*** the textual name given to a registered field





## Notes

The field with name fieldname must be defined as having a data type of PetscScalar.

This function must be called prior to calling DMCreateLocalVector(), DMCreateGlobalVector().
Multiple calls to DMSwarmVectorDefineField() are permitted.


## See Also
 `DMSwarmRegisterPetscDatatypeField()`, `DMCreateGlobalVector()`, `DMCreateLocalVector()`

## Level
beginner

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

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/tutorials/swarm_ex1.c.html">src/dm/tutorials/swarm_ex1.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/tutorials/swarm_ex2.c.html">src/dm/tutorials/swarm_ex2.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/snes/tutorials/ex63.c.html">src/snes/tutorials/ex63.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ts/tutorials/ex77.c.html">src/ts/tutorials/ex77.c.html</A><BR>


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


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