petsc-3.3-p7 2013-05-11

MatFDColoringSetFromOptions

Sets coloring finite difference parameters from the options database.

Synopsis

#include "petscmat.h" 
PetscErrorCode  MatFDColoringSetFromOptions(MatFDColoring matfd)

Collective on MatFDColoring

The Jacobian, F'(u), is estimated with the differencing approximation

       F'(u)_{:,i} = [F(u+h*dx_{i}) - F(u)]/h where
       h = error_rel*u[i]                 if  abs(u[i]) > umin
         = +/- error_rel*umin             otherwise, with +/- determined by the sign of u[i]
       dx_{i} = (0, ... 1, .... 0)

Input Parameter

coloring -the coloring context

Options Database Keys

	-mat_fd_coloring_err <err>	- Sets <err> (square root of relative error in the function)
	-mat_fd_coloring_umin <umin>	- Sets umin, the minimum allowable u-value magnitude
	-mat_fd_type	- "wp" or "ds" (see MATMFFD_WP or MATMFFD_DS)
	-mat_fd_coloring_view	- Activates basic viewing
	-mat_fd_coloring_view_info	- Activates viewing info
	-mat_fd_coloring_view_draw	- Activates drawing

Keywords

Mat, finite differences, parameters

Examples