functions in rays.i - f

    best= form_rays( [x, y, z, theta, phi] )  
 or dirt= form_rays( [x, y, theta] )  
 or internal= form_rays( [cos, sin, y, z, x, r] )  


forms 5-by-nrays, 3-by-nrays, or 6-by-nrays ray representation  
given individual lists of array coordinates.  The [...]  
operator builds an nrays-by-5, nrays-by-3, or nrays-by-6  
array, which form_rays transposes.  The "nrays" may represent  
zero or more actual dimensions.  
Interpreted function, defined at i/rays.i   line 27