function varargout = dfgui(varargin)
 
  $Id: dfgui.m,v 1.100 2003-08-26 09:21:19-05 brinkman Exp $
  (c) 2002, Peter Brinkmann (brinkman@math.uiuc.edu)
 
  dfgui: Graphical user interface for Iode's direction fields modules
 
  Usage:
 	fig = dfgui
 			 launch GUI
 	dfgui('callback_name', ...)
 			 invoke the named callback
 
  Many thanks to Richard Laugesen for valuable feedback and suggestions!