Incomplete work for using Boost.Polygon to compute medial axis

xs/src/boost/ratio/mpl/rational_c_tag.hpp

@@ -0,0 +1,25 @@
+//  abs.hpp
+//
+//  (C) Copyright 2011 Vicente J. Botet Escriba
+//  Use, modification and distribution are subject to the Boost Software License,
+//  Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+//  http://www.boost.org/LICENSE_1_0.txt).
+//
+
+#ifndef BOOST_RATIO_MPL_RATIONAL_C_TAG_HPP
+#define BOOST_RATIO_MPL_RATIONAL_C_TAG_HPP
+
+#ifdef BOOST_RATIO_EXTENSIONS
+
+#include <boost/mpl/int.hpp>
+
+namespace boost {
+namespace mpl {
+
+struct rational_c_tag : int_<10> {};
+
+}
+}
+
+#endif // BOOST_RATIO_EXTENSIONS
+#endif  // BOOST_RATIO_MPL_RATIONAL_C_TAG_HPP