petsc-master 2018-05-24
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MatFDColoringSetParameters

Sets the parameters for the sparse approximation of a Jacobian matrix using finite differences.

Synopsis

#include "petscmat.h" 
PetscErrorCode MatFDColoringSetParameters(MatFDColoring matfd,PetscReal error,PetscReal umin)
Logically Collective on MatFDColoring

The Jacobian is estimated with the differencing approximation

       F'(u)_{:,i} = [F(u+h*dx_{i}) - F(u)]/h where
       htype = 'ds':
         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)

       htype = 'wp':
         h = error_rel * sqrt(1 + ||u||)

Input Parameters

coloring - the coloring context
error_rel - relative error
umin - minimum allowable u-value magnitude

Keywords

Mat, finite differences, coloring, set, parameters

See Also

MatFDColoringCreate(), MatFDColoringSetFromOptions()

Level

advanced

Location

src/mat/matfd/fdmatrix.c
Index of all MatFD routines
Table of Contents for all manual pages
Index of all manual pages