(C.4) |

(C.5) | ||||

(C.6) | ||||

(C.7) |

Using the product representation of the cosine function (C.2):

(C.8) | ||||

(C.9) |

Since all factors of this product series are in the range , it is sufficient to show that:

(C.10) | ||||

(C.11) |

Using for all :

(C.12) | ||||

(C.13) | ||||

(C.14) |

Using again :

(C.15) | ||||

(C.16) | ||||

(C.17) |

Otmar Ertl: Numerical Methods for Topography Simulation