#include "petscpc.h" PetscErrorCode PCFactorSetMatOrderingType(PC pc,MatOrderingType ordering)Logically Collective on PC
|pc||- the preconditioner context|
|ordering||- the matrix ordering name, for example, MATORDERINGND or MATORDERINGRCM|
|-pc_factor_mat_ordering_type <nd,rcm,...,external>||- Sets ordering routine|
For Cholesky and ICC and the SBAIJ format the only reordering available is natural since only the upper half of the matrix is stored and reordering this matrix is very expensive.
You can use SeqAIJ matrix with Cholesky and ICC and use any ordering
external means PETSc will not compute an ordering and the package will use its own ordering, for MATSOLVERCHOLMOD and MATSOLVERUMFPACK