:orphan:
# DMPlexSetClosurePermutationTensor
Create a permutation from the default (BFS) point ordering in the closure, to a lexicographic ordering over the tensor product cell (i.e., line, quad, hex, etc.), and set this permutation in the section provided (or the section of the `DM`).
## Synopsis
```
#include "petscdmplex.h"
PetscErrorCode DMPlexSetClosurePermutationTensor(DM dm, PetscInt point, PetscSection section)
```
## Input Parameters
- ***dm -*** The `DM`
- ***point -*** Either a cell (highest dim point) or an edge (dim 1 point), or `PETSC_DETERMINE`
- ***section -*** The `PetscSection` to reorder, or `NULL` for the default section
## Example
A typical interpolated single-quad mesh might order points as
```none
[c0, v1, v2, v3, v4, e5, e6, e7, e8]
v4 -- e6 -- v3
| |
e7 c0 e8
| |
v1 -- e5 -- v2
```
(There is no significance to the ordering described here.) The default section for a Q3 quad might typically assign
dofs in the order of points, e.g.,
```none
c0 -> [0,1,2,3]
v1 -> [4]
...
e5 -> [8, 9]
```
which corresponds to the dofs
```none
6 10 11 7
13 2 3 15
12 0 1 14
4 8 9 5
```
The closure in BFS ordering works through height strata (cells, edges, vertices) to produce the ordering
```none
0 1 2 3 8 9 14 15 11 10 13 12 4 5 7 6
```
After calling DMPlexSetClosurePermutationTensor(), the closure will be ordered lexicographically,
```none
4 8 9 5 12 0 1 14 13 2 3 15 6 10 11 7
```
## Note
The point is used to determine the number of dofs/field on an edge. For SEM, this is related to the polynomial
degree of the basis.
## See Also
[](ch_unstructured), `DM`, `DMPLEX`, `DMGetLocalSection()`, `PetscSectionSetClosurePermutation()`, `DMSetGlobalSection()`
## Level
developer
## Location
src/dm/impls/plex/plex.c
## Examples
src/dm/impls/plex/tutorials/ex6.c
src/dm/impls/plex/tutorials/ex8.c
---
[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/dm/impls/plex/plex.c)
[Index of all DMPlex routines](index.md)
[Table of Contents for all manual pages](/manualpages/index.md)
[Index of all manual pages](/manualpages/singleindex.md)