MatColoringCreate#

Creates a matrix coloring context.

Synopsis#

#include "petscmat.h"  
PetscErrorCode MatColoringCreate(Mat m, MatColoring *mcptr)

Collective

Input Parameter#

comm - MPI communicator

Output Parameter#

mcptr - the new MatColoring context

Options Database Keys#

-mat_coloring_type - the type of coloring algorithm used. See MatColoringType.
-mat_coloring_maxcolors - the maximum number of relevant colors, all nodes not in a color are in maxcolors+1
-mat_coloring_distance - compute a distance 1,2,… coloring.
-mat_coloring_view - print information about the coloring and the produced index sets
-mat_coloring_test - debugging option that prints all coloring incompatibilities
-mat_is_coloring_test - debugging option that throws an error if MatColoringApply() generates an incorrect iscoloring

Notes#

A distance one coloring is useful, for example, multi-color SOR.

A distance two coloring is for the finite difference computation of Jacobians (see MatFDColoringCreate()).

Coloring of matrices can be computed directly from the sparse matrix nonzero structure via the MatColoring object or from the mesh from which the matrix comes from with DMCreateColoring(). In general using the mesh produces a more optimal coloring (fewer colors).

Some coloring types only support distance two colorings