#include "petscmat.h" PetscErrorCode MatMFFDSetPeriod(Mat mat,PetscInt period)Logically Collective on Mat Many br
| mat | - the matrix free matrix created via MatCreateSNESMF() Many br | |
| period | - 1 for everytime, 2 for every second etc Many br |
| -mat_mffd_period <period> | - Many br Many br |