function varargout = ppgui(varargin)
 
  $Id: ppgui.m,v 1.87 2003-08-26 09:21:19-05 brinkman Exp $
  (c) 2002, Peter Brinkmann (brinkman@math.uiuc.edu)
 
  ppgui: Graphical user interface for Iode's phase plane modules
 
  Usage:
 	fig = ppgui
 			 launch GUI.
 	ppgui('callback_name', ...)
 			 invoke the named callback.
 
  Many thanks to Richard Laugesen for valuable feedback and suggestions!