Symmetries of the data referenced by a
typedef struct _p_PetscSectionSym *PetscSectionSym;
Often the order of data index by a
PetscSection is meaningful, and describes additional structure, such as points on a
line, grid, or lattice. If the data is accessed from a different “orientation”, then the image of the data under
access then undergoes a symmetry transformation. A
PetscSectionSym specifies these symmetries. The types of
symmetries that can be specified are of the form R * P, where R is a diagonal matrix of scalars, and P is a permutation.