Application: gvSIG desktop

#ifndef lint

static const char SCCSID[]="@(#)PJ_cea.c        4.1        94/02/15        GIE        REL";

#endif

#define PROJ_PARMS__ \

        double qp; \

        double *apa;

#define PJ_LIB__

# include        <projects.h>

PROJ_HEAD(cea, "Equal Area Cylindrical") "\n\tCyl, Sph&Ell\n\tlat_ts=";

# define EPS        1e-10

FORWARD(e_forward); /* spheroid */

        xy.x = P->k0 * lp.lam;

        xy.y = .5 * pj_qsfn(sin(lp.phi), P->e, P->one_es) / P->k0;

        return (xy);

}

FORWARD(s_forward); /* spheroid */

        xy.x = P->k0 * lp.lam;

        xy.y = sin(lp.phi) / P->k0;

        return (xy);

}

INVERSE(e_inverse); /* spheroid */

        lp.phi = pj_authlat(asin( 2. * xy.y * P->k0 / P->qp), P->apa);

        lp.lam = xy.x / P->k0;

        return (lp);

}

INVERSE(s_inverse); /* spheroid */

        double t;

        if ((t = fabs(xy.y *= P->k0)) - EPS <= 1.) {

                if (t >= 1.)

                        lp.phi = xy.y < 0. ? -HALFPI : HALFPI;

                else

                        lp.phi = asin(xy.y);

                lp.lam = xy.x / P->k0;

        } else I_ERROR;

        return (lp);

}

FREEUP;

        if (P) {

                if (P->apa)

                        pj_dalloc(P->apa);

                pj_dalloc(P);

        }

}

ENTRY1(cea, apa)

        double t;

        if (pj_param(P->params, "tlat_ts").i &&

                (P->k0 = cos(t = pj_param(P->params, "rlat_ts").f)) < 0.) E_ERROR(-24)

        else

                t = 0.;

        if (P->es) {

                t = sin(t);

                P->k0 /= sqrt(1. - P->es * t * t);

                P->e = sqrt(P->es);

                if (!(P->apa = pj_authset(P->es))) E_ERROR_0;

                P->qp = pj_qsfn(1., P->e, P->one_es);

                P->inv = e_inverse;

                P->fwd = e_forward;

        } else {

                P->inv = s_inverse;

                P->fwd = s_forward;

        }

ENDENTRY(P)