(93) |

Inserting in equation 85, gives

(94) |

(95) |

(96) |

Which is the same result as obtained in [2].

These equations become:

(97) |

and

(98) |

Accounting for propagation we can write. Note the change in sign between [2] and this work, this is because of how I have defined my wave equation.

(99) |

and

(100) |

where

(101) |

The boundary condition on the right hand side is given by:

(102) |

where we say that is zero and is zero. Therefore we end up with

(103) |

as the boundary condition.