MATMFFD_WP#
Implements an approach for computing the differencing parameter h used with the finite difference based matrix-free Jacobian. h = error_rel * sqrt(1 + ||U||) / ||a||
Options Database Key#
-mat_mffd_compute_normu - Compute the norm of u every time see
MatMFFDWPSetComputeNormU()
Notes#
|| U || does not change between linear iterations so is reused
In KSPGMRES || a || == 1 and so does not need to ever be computed except at restart
when it is recomputed. Thus equires no global collectives when used with KSPGMRES
Formula used#
F’(u)a = [F(u+ha) - F(u)]/h where
Reference#
**** -*** M. Pernice and H. F. Walker, “NITSOL: A Newton Iterative Solver for Nonlinear Systems”, SIAM J. Sci. Stat. Comput.”, 1998, vol 19, pp. 302–318.
See Also#
MATMFFD, MATMFFD_DS, MatCreateMFFD(), MatCreateSNESMF(), MATMFFD_DS
Level#
intermediate
Location#
Index of all Mat routines
Table of Contents for all manual pages
Index of all manual pages