projections/impl/pj_tsfn.hpp

0001 // Boost.Geometry (aka GGL, Generic Geometry Library)
0002 // This file is manually converted from PROJ4
0003
0004 // Copyright (c) 2008-2012 Barend Gehrels, Amsterdam, the Netherlands.
0005
0006 // This file was modified by Oracle on 2017, 2018.
0007 // Modifications copyright (c) 2017-2018, Oracle and/or its affiliates.
0008 // Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
0009
0010 // Use, modification and distribution is subject to the Boost Software License,
0011 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
0012 // http://www.boost.org/LICENSE_1_0.txt)
0013
0014 // This file is converted from PROJ4, http://trac.osgeo.org/proj
0015 // PROJ4 is originally written by Gerald Evenden (then of the USGS)
0016 // PROJ4 is maintained by Frank Warmerdam
0017 // PROJ4 is converted to Geometry Library by Barend Gehrels (Geodan, Amsterdam)
0018
0019 // Original copyright notice:
0020
0021 // Permission is hereby granted, free of charge, to any person obtaining a
0022 // copy of this software and associated documentation files (the "Software"),
0023 // to deal in the Software without restriction, including without limitation
0024 // the rights to use, copy, modify, merge, publish, distribute, sublicense,
0025 // and/or sell copies of the Software, and to permit persons to whom the
0026 // Software is furnished to do so, subject to the following conditions:
0027
0028 // The above copyright notice and this permission notice shall be included
0029 // in all copies or substantial portions of the Software.
0030
0031 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
0032 // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
0033 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
0034 // THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
0035 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
0036 // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
0037 // DEALINGS IN THE SOFTWARE.
0038
0039 #ifndef BOOST_GEOMETRY_PROJECTIONS_PJ_TSFN_HPP
0040 #define BOOST_GEOMETRY_PROJECTIONS_PJ_TSFN_HPP
0041
0042 #include <boost/geometry/util/math.hpp>
0043
0044 namespace boost { namespace geometry { namespace projections {
0045 namespace detail {
0046
0047     /* determine small t */
0048     template <typename T>
0049     inline T pj_tsfn(T const& phi, T sinphi, T const& e)
0050     {
0051         sinphi *= e;
0052         return (tan (.5 * (geometry::math::half_pi<T>() - phi)) /
0053            math::pow((T(1) - sinphi) / (T(1) + sinphi), T(0.5) * e));
0054     }
0055
0056 } // namespace detail
0057 }}} // namespace boost::geometry::projections
0058 #endif