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

Input Parameters#

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

Note#

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||)

See Also#

Mat, MatFDColoring, MatFDColoringCreate(), MatFDColoringSetFromOptions()

Level#

advanced

Location#

src/mat/matfd/fdmatrix.c

Index of all MatFD routines
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Index of all manual pages