# MatSNESMFWPSetComputeNormU

Sets whether it computes the ||U|| used by the WP PETSc routine for computing h. With any Krylov solver this need only be computed during the first iteration and kept for later.

### Synopsis

    #include "petscsnes.h"
    PetscErrorCode PETSCSNES_DLLEXPORT MatSNESMFWPSetComputeNormU(Mat A,PetscTruth flag)

### Input Parameters

| A | - the matrix created with MatCreateSNESMF()
| flag | - PETSC_TRUE causes it to compute ||U||, PETSC_FALSE uses the previous value

### Options Database Key

-snes_mf_compute_normu <true,false> -true by default, false causes extra calculations

### 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/wp.c
Index of all SNESMF routines
Table of Contents for all manual pages
Index of all manual pages