#include <math.h>

#include "proj.h"

#include "proj_internal.h"

PROJ_HEAD(tcc, "Transverse Central Cylindrical") "\n\tCyl, Sph, no inv";

#define EPS10 1.e-10

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

    PJ_XY xy = {0.0, 0.0};

    const double b = cos(lp.phi) * sin(lp.lam);

    const double bt = 1. - b * b;

    if (bt < EPS10) {

        proj_errno_set(P, PROJ_ERR_COORD_TRANSFM_OUTSIDE_PROJECTION_DOMAIN);

        return xy;

    }

    xy.x = b / sqrt(bt);

    xy.y = atan2(tan(lp.phi), cos(lp.lam));

    return xy;

}

PJ *PJ_PROJECTION(tcc) {

    P->es = 0.;

    P->fwd = tcc_s_forward;

    P->inv = nullptr;

    return P;

}