MatMFFDSetType#

Sets the method that is used to compute the differencing parameter for finite difference matrix-free formulations.

Synopsis#

#include "petscmat.h"   
PetscErrorCode MatMFFDSetType(Mat mat, MatMFFDType ftype)

mat - the “matrix-free” matrix created via MatCreateSNESMF(), or MatCreateMFFD() or MatSetType(mat,MATMFFD);
ftype - the type requested, either MATMFFD_WP or MATMFFD_DS

For example, such routines can compute h for use in Jacobian-vector products of the form

                        F(x+ha) - F(x)
          F'(u)a  ~=  ----------------
                              h

advanced