Utility functions for this application

Invent this function 17/2/2006 - I previous had the same operations in several different places.
11/5/2006 take the aperture value from the end rather than the centre of the element (I just deleted the term calculating 1/2 the length).

The following modelled on madLHCBoilerPlate

Surely this is not necessary ?

Created by Wolfram Mathematica 6.0  (30 August 2007)