# PETSCSPACESUM
"sum" - A `PetscSpace` object that encapsulates a sum of subspaces. That sum can either be direct or concatenate a concatenation. For example if A and B are spaces each with 2 components, the direct sum of A and B will also have 2 components while the concatenated sum will have 4 components.In both cases A and B must be defined over the same number of variables. 


## See Also
 `PetscSpace`, `PetscSpaceType`, `PetscSpaceCreate()`, `PetscSpaceSetType()`

## Level
intermediate

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/dt/space/impls/sum/spacesum.c.html#PETSCSPACESUM">src/dm/dt/space/impls/sum/spacesum.c</A>


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


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