// Generic Geometry Library - projections (based on PROJ4)
// This file is manually converted from PROJ4

// Copyright Barend Gehrels 1995-2009, Geodan Holding B.V. Amsterdam, the Netherlands.
// Copyright Bruno Lalande 2008, 2009
// 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)

// This file is converted from PROJ4, http://trac.osgeo.org/proj
// PROJ4 is originally written by Gerald Evenden (then of the USGS)
// PROJ4 is maintained by Frank Warmerdam
// PROJ4 is converted to Geometry Library by Barend Gehrels (Geodan, Amsterdam)

// Original copyright notice:

// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:

// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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// DEALINGS IN THE SOFTWARE.

#ifndef GGL_PROJECTIONS_IMPL_PJ_AUTH_HPP
#define GGL_PROJECTIONS_IMPL_PJ_AUTH_HPP

#include <cassert>
#include <cmath>

namespace ggl { namespace projection { namespace detail {

static const double P00 = .33333333333333333333;
static const double P01 = .17222222222222222222;
static const double P02 = .10257936507936507936;
static const double P10 = .06388888888888888888;
static const double P11 = .06640211640211640211;
static const double P20 = .01641501294219154443;
static const int APA_SIZE = 3;

/* determine latitude from authalic latitude */
inline void pj_authset(double es, double* APA)
{
    assert(0 != APA);

    double t = 0;

    // if (APA = (double *)pj_malloc(APA_SIZE * sizeof(double)))
    {
        APA[0] = es * P00;
        t = es * es;
        APA[0] += t * P01;
        APA[1] = t * P10;
        t *= es;
        APA[0] += t * P02;
        APA[1] += t * P11;
        APA[2] = t * P20;
    }
}

inline double pj_authlat(double beta, const double* APA)
{
    assert(0 != APA);

    const double t = beta + beta;

    return(beta + APA[0] * std::sin(t) + APA[1] * std::sin(t + t) + APA[2] * std::sin(t + t + t));
}

}}} // namespace ggl::projection::impl

#endif // GGL_PROJECTIONS_IMPL_PJ_AUTH_HPP
