83rd example.  Same as xmpl3d06, but without automatic iteration to optimise a focus, and with outputting of data for re-use as imported data for xmpl3d84.

 The data for re-use is in a grid that covers the region x,y = 0 to 0.13,  z = -4.05 to 0.   The grid has potentials and fields and is output to the ray output file  temp83a.dat.

 These potentials and fields are re-used in xmpl3d84.