(3.11) |

The discretized representation is obtained by replacing the second order derivative by the central difference quotient eqn. (3.10) at all inner points

(3.12) |

The equations for and are determined by the boundary conditions. By rewriting this equation in the form

the coefficients are found to be

(3.14) | ||||

(3.15) |

The coefficient matrix resulting from the linear equation system eqn. (3.13) is symmetric and only the diagonal and the secondary diagonal are filled with elements different from zero.