To accomplish this the respective part of the transformation matrix reads

t_{x, y} |
||

1 | ||

1 |

which is actually the default case and hence needs not to be explicitly specified.

The derivatives of the flux term with respect to the solution variables must
be of the same magnitude as the other derivatives given by
*f*^{S}_{} in
order to guarantee good conditioning of the resulting equation system
[15]. Since this cannot generally be guaranteed, an approach similar
to Dirichlet interfaces is preferable [63]: Adding
(5.9) to (5.10) one gets

As for Dirichlet interfaces, (5.11) is pre-eliminated before the actual iterative solution process. The appropriate transformation matrix reads

t_{x, y} |
||

1 | ||

1 | 1 |

1999-05-31