// Boost.Geometry (aka GGL, Generic Geometry Library)
// This file is manually converted from PROJ4

// Copyright (c) 2008-2012 Barend Gehrels, Amsterdam, the Netherlands.

// 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
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.

#ifndef BOOST_GEOMETRY_PROJECTIONS_PJ_MLFN_HPP
#define BOOST_GEOMETRY_PROJECTIONS_PJ_MLFN_HPP



#include <boost/geometry/util/math.hpp>


namespace boost { namespace geometry { namespace projections {

namespace detail {

/* meridinal distance for ellipsoid and inverse
**    8th degree - accurate to < 1e-5 meters when used in conjuction
**        with typical major axis values.
**    Inverse determines phi to EPS (1e-11) radians, about 1e-6 seconds.
*/
static const double C00 = 1.;
static const double C02 = .25;
static const double C04 = .046875;
static const double C06 = .01953125;
static const double C08 = .01068115234375;
static const double C22 = .75;
static const double C44 = .46875;
static const double C46 = .01302083333333333333;
static const double C48 = .00712076822916666666;
static const double C66 = .36458333333333333333;
static const double C68 = .00569661458333333333;
static const double C88 = .3076171875;
static const double EPS = 1e-11;
static const int MAX_ITER = 10;
static const int EN_SIZE = 5;

inline void pj_enfn(double es, double* en)
{
    double t; //, *en;

    //if (en = (double *)pj_malloc(EN_SIZE * sizeof(double)))
    {
        en[0] = C00 - es * (C02 + es * (C04 + es * (C06 + es * C08)));
        en[1] = es * (C22 - es * (C04 + es * (C06 + es * C08)));
        en[2] = (t = es * es) * (C44 - es * (C46 + es * C48));
        en[3] = (t *= es) * (C66 - es * C68);
        en[4] = t * es * C88;
    }
    // return en;
}

inline double pj_mlfn(double phi, double sphi, double cphi, const double *en)
{
    cphi *= sphi;
    sphi *= sphi;
    return(en[0] * phi - cphi * (en[1] + sphi*(en[2]
        + sphi*(en[3] + sphi*en[4]))));
}

inline double pj_inv_mlfn(double arg, double es, const double *en)
{
    double s, t, phi, k = 1./(1.-es);
    int i;

    phi = arg;
    for (i = MAX_ITER; i ; --i) { /* rarely goes over 2 iterations */
        s = sin(phi);
        t = 1. - es * s * s;
        phi -= t = (pj_mlfn(phi, s, cos(phi), en) - arg) * (t * sqrt(t)) * k;
        if (geometry::math::abs(t) < EPS)
            return phi;
    }
    throw proj_exception(-17);
    return phi;
}

} // namespace detail
}}} // namespace boost::geometry::projections

#endif
