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# PetscSectionCreateSubmeshSection
Create a new, smaller section with support on the submesh 
## Synopsis
```
#include "petscsection.h"   
PetscErrorCode PetscSectionCreateSubmeshSection(PetscSection s, IS subpointMap, PetscSection *subs)
```
Collective


## Input Parameters

- ***s           -*** the `PetscSection`
- ***subpointMap -*** a sorted list of points in the original mesh which are in the submesh



## Output Parameter

- ***subs -*** the subsection





## Notes
The points are renumbered from 0, and the section offsets now refer to a new, smaller vector. That is the chart of `subs` is `[0,sizeof(subpointmap))`

Compare this with `PetscSectionCreateSubdomainSection()` that does not map the points numbers to start at zero but leaves them as before


## Developer Note
The use of the term Submesh is confusing and needs clarification, it is not specific to meshes. It appears to be just a subset of the chart of the original `PetscSection`


## See Also
 [PetscSection](sec_petscsection), `PetscSection`, `PetscSectionCreateSubdomainSection()`, `PetscSectionCreateSubsection()`, `DMPlexGetSubpointMap()`, `PetscSectionCreate()`

## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/is/section/interface/section.c.html#PetscSectionCreateSubmeshSection">src/vec/is/section/interface/section.c</A>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/vec/is/section/interface/section.c)


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