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+// Boost.Geometry
+
+// Copyright (c) 2014-2016 Oracle and/or its affiliates.
+
+// Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
+
+// Use, modification and distribution is 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_GEOMETRY_FORMULAS_FLATTENING_HPP
+#define BOOST_GEOMETRY_FORMULAS_FLATTENING_HPP
+
+#include <boost/geometry/core/radius.hpp>
+#include <boost/geometry/core/tag.hpp>
+#include <boost/geometry/core/tags.hpp>
+
+#include <boost/geometry/algorithms/not_implemented.hpp>
+
+namespace boost { namespace geometry
+{
+
+#ifndef DOXYGEN_NO_DISPATCH
+namespace formula_dispatch
+{
+
+template <typename ResultType, typename Geometry, typename Tag = typename tag<Geometry>::type>
+struct flattening
+ : not_implemented<Tag>
+{};
+
+template <typename ResultType, typename Geometry>
+struct flattening<ResultType, Geometry, srs_sphere_tag>
+{
+ static inline ResultType apply(Geometry const& /*geometry*/)
+ {
+ return ResultType(0);
+ }
+};
+
+template <typename ResultType, typename Geometry>
+struct flattening<ResultType, Geometry, srs_spheroid_tag>
+{
+ static inline ResultType apply(Geometry const& geometry)
+ {
+ // (a - b) / a
+ return ResultType(get_radius<0>(geometry) - get_radius<2>(geometry))
+ / ResultType(get_radius<0>(geometry));
+ }
+};
+
+} // namespace formula_dispatch
+#endif // DOXYGEN_NO_DISPATCH
+
+#ifndef DOXYGEN_NO_DETAIL
+namespace formula
+{
+
+template <typename ResultType, typename Geometry>
+ResultType flattening(Geometry const& geometry)
+{
+ return formula_dispatch::flattening<ResultType, Geometry>::apply(geometry);
+}
+
+} // namespace formula
+#endif // DOXYGEN_NO_DETAIL
+
+}} // namespace boost::geometry
+
+#endif // BOOST_GEOMETRY_FORMULAS_FLATTENING_HPP