computation of conformal maps to polygonally bounded regions

				function M = inv(Mi)
				%INV    Original SC map from its inverse.
				%   INV(MI) just returns the SC map that was originally inverted to
				%   produce MI. 
				
				%   Copyright 1998 by Toby Driscoll.
				%   $Id: inv.m 7 1998-05-10 04:37:19Z tad $
				
				M = Mi.themap;