  function eint = edgeint (u)
% function eint = edgeint (u)
% Integrand needed in edge diffraction integral, Eq. (24) in 
% the note about Fresnel diffraction 
% Computes integrand to be used with script edgediffraction
% Input:  
%  u  array of values to compute integrand for
%     normalized position in aperture
% Output: 
%  eint  array of corresponding values for the integrand
eint  =  exp (-0.5.*j.*pi.*u.^2); 
return