Vaucanson, a generic library for finite state machines.
Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007 The Vaucanson Group.

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

The complete GNU General Public Licence Notice can be found as the
'COPYING' file in the root directory.

The Vaucanson Group consists of people listed in the 'AUTHORS' file.

=======================================
 Vaucanson_ Frequently Asked Questions
=======================================

:Date: March 2006

Here are answers  to different questions you may  have while compiling
or using Vaucanson_.

.. _Vaucanson: http://vaucanson.lrde.epita.fr

.. contents::

Compilation Problems
====================

I have a "NAN undeclared" error. What can I do?
-----------------------------------------------

Your C++ compiler does not  support the C99 standard library.  This is
a  known bug  (``NAN`` should  not be  used without  checking  for its
existence  before)  and will  be  corrected.   Meanwhile, use  another
compiler, such as the `GNU C++ Compiler`_ version 3.3 or above.

.. _GNU C++ Compiler: http://gcc.gnu.org

I have a conflit declaration for ``int getopt()``.
--------------------------------------------------

The   flag   ``HAVE_DECL_GETOPT``    must   be   set.   Compile   with
``-DHAVE_DECL_GETOPT``.    To   use   this   flag  with   the   script
``configure``, call it with::

   configure CPPFLAGS='-DHAVE_DECL_GETOPT'

Usage issues
============

The expression parser behave incorrectly on some expressions
------------------------------------------------------------

For example, expressions  with weights such as ``a  2*`` (meaning "the
star of ``a`` with weight 2) are not parsed correctly.

Solution: write ``(a 2)*`` instead. This  problem is due to the use of
LL  parsing,   which  cannot  handle  expressions   like  the  example
above. This  is a known  misfeature, that cannot be  corrected without
making  the code  bigger and  slower.  Since a  very readable,  simple
workaround exists, use it instead.

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