# MatSNESMFDefaultSetUmin

Sets the "umin" parameter used by the default PETSc routine for computing the differencing parameter, h, which is used for matrix-free Jacobian-vector products.

### Synopsis

    #include "petscsnes.h"
    PetscErrorCode PETSCSNES_DLLEXPORT MatSNESMFDefaultSetUmin(Mat A,PetscReal umin)

### Input Parameters

| A | - the matrix created with MatCreateSNESMF()
| umin | - the parameter

### Notes

See the manual page for MatCreateSNESMF() for a complete description of the algorithm used to compute h.

### See Also

MatSNESMFSetFunctionError(), MatCreateSNESMF()

Level:advanced
Location:src/snes/mf/snesmfjdef.c
Index of all SNESMF routines
Table of Contents for all manual pages
Index of all manual pages