1 // Boost.Geometry (aka GGL, Generic Geometry Library)
2 // This file is manually converted from PROJ4
3
4 // Copyright (c) 2008-2012 Barend Gehrels, Amsterdam, the Netherlands.
5
6 // This file was modified by Oracle on 2017, 2018.
7 // Modifications copyright (c) 2017-2018, Oracle and/or its affiliates.
8 // Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
9
10 // Use, modification and distribution is subject to the Boost Software License,
11 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
12 // http://www.boost.org/LICENSE_1_0.txt)
13
14 // This file is converted from PROJ4, http://trac.osgeo.org/proj
15 // PROJ4 is originally written by Gerald Evenden (then of the USGS)
16 // PROJ4 is maintained by Frank Warmerdam
17 // PROJ4 is converted to Geometry Library by Barend Gehrels (Geodan, Amsterdam)
18
19 // Original copyright notice:
20
21 // Permission is hereby granted, free of charge, to any person obtaining a
22 // copy of this software and associated documentation files (the "Software"),
23 // to deal in the Software without restriction, including without limitation
24 // the rights to use, copy, modify, merge, publish, distribute, sublicense,
25 // and/or sell copies of the Software, and to permit persons to whom the
26 // Software is furnished to do so, subject to the following conditions:
27
28 // The above copyright notice and this permission notice shall be included
29 // in all copies or substantial portions of the Software.
30
31 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
32 // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
33 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
34 // THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
35 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
36 // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
37 // DEALINGS IN THE SOFTWARE.
38
39 #ifndef BOOST_GEOMETRY_PROJECTIONS_PHI2_HPP
40 #define BOOST_GEOMETRY_PROJECTIONS_PHI2_HPP
41
42 #include <boost/geometry/srs/projections/exception.hpp>
43 #include <boost/geometry/srs/projections/impl/pj_strerrno.hpp>
44 #include <boost/geometry/util/math.hpp>
45
46 namespace boost { namespace geometry { namespace projections {
47 namespace detail {
48
49 template <typename T>
pj_phi2(T const & ts,T const & e)50 inline T pj_phi2(T const& ts, T const& e)
51 {
52 static const T TOL = 1.0e-10;
53 static const int N_ITER = 15;
54
55 T eccnth, Phi, con, dphi;
56 int i;
57
58 eccnth = .5 * e;
59 Phi = geometry::math::half_pi<T>() - 2. * atan (ts);
60 i = N_ITER;
61 do {
62 con = e * sin (Phi);
63 dphi = geometry::math::half_pi<T>() - 2. * atan (ts * math::pow((T(1) - con) /
64 (T(1) + con), eccnth)) - Phi;
65 Phi += dphi;
66 } while ( geometry::math::abs(dphi) > TOL && --i);
67 if (i <= 0)
68 BOOST_THROW_EXCEPTION( projection_exception(error_non_con_inv_phi2) );
69 return Phi;
70 }
71
72 } // namespace detail
73 }}} // namespace boost::geometry::projections
74
75 #endif
76