petsc-3.12.5 2020-03-29

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

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.

Example

A typical interpolated single-quad mesh might order points as

  [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.,

    c0 -> [0,1,2,3]
    v1 -> [4]
    ...
    e5 -> [8, 9]

which corresponds to the dofs

    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

  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,

   4 8 9 5 12 0 1 14 13 2 3 15 6 10 11 7

Level

developer

Location