#include <math.h>

#include "proj.h"

#include "proj_internal.h"

PROJ_HEAD(mill, "Miller Cylindrical") "\n\tCyl, Sph";

static PJ_XY mill_s_forward(PJ_LP lp, PJ *P) { /* Spheroidal, forward */

    PJ_XY xy = {0.0, 0.0};

    (void)P;

    xy.x = lp.lam;

    xy.y = log(tan(M_FORTPI + lp.phi * .4)) * 1.25;

    return (xy);

}

static PJ_LP mill_s_inverse(PJ_XY xy, PJ *P) { /* Spheroidal, inverse */

    PJ_LP lp = {0.0, 0.0};

    (void)P;

    lp.lam = xy.x;

    lp.phi = 2.5 * (atan(exp(.8 * xy.y)) - M_FORTPI);

    return (lp);

}

PJ *PJ_PROJECTION(mill) {

    P->es = 0.;

    P->inv = mill_s_inverse;

    P->fwd = mill_s_forward;

    return P;

}