Application: gvSIG desktop

#ifndef lint

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

#endif

#define PROJ_PARMS__ \

        double        theta; \

        double        m, n; \

        double        two_r_m, two_r_n, rm, rn, hm, hn; \

        double        cp0, sp0;

#define PJ_LIB__

#include        <projects.h>

PROJ_HEAD(oea, "Oblated Equal Area") "\n\tMisc Sph\n\tn= m= theta=";

FORWARD(s_forward); /* sphere */

        double Az, M, N, cp, sp, cl, shz;

        cp = cos(lp.phi);

        sp = sin(lp.phi);

        cl = cos(lp.lam);

        Az = aatan2(cp * sin(lp.lam), P->cp0 * sp - P->sp0 * cp * cl) + P->theta;

        shz = sin(0.5 * aacos(P->sp0 * sp + P->cp0 * cp * cl));

        M = aasin(shz * sin(Az));

        N = aasin(shz * cos(Az) * cos(M) / cos(M * P->two_r_m));

        xy.y = P->n * sin(N * P->two_r_n);

        xy.x = P->m * sin(M * P->two_r_m) * cos(N) / cos(N * P->two_r_n);

        return (xy);

}

INVERSE(s_inverse); /* sphere */

        double N, M, xp, yp, z, Az, cz, sz, cAz;

        N = P->hn * aasin(xy.y * P->rn);

        M = P->hm * aasin(xy.x * P->rm * cos(N * P->two_r_n) / cos(N));

        xp = 2. * sin(M);

        yp = 2. * sin(N) * cos(M * P->two_r_m) / cos(M);

        cAz = cos(Az = aatan2(xp, yp) - P->theta);

        z = 2. * aasin(0.5 * hypot(xp, yp));

        sz = sin(z);

        cz = cos(z);

        lp.phi = aasin(P->sp0 * cz + P->cp0 * sz * cAz);

        lp.lam = aatan2(sz * sin(Az),

                P->cp0 * cz - P->sp0 * sz * cAz);

        return (lp);

}

FREEUP; if (P) pj_dalloc(P); }

ENTRY0(oea)

        if (((P->n = pj_param(P->params, "dn").f) <= 0.) ||

                ((P->m = pj_param(P->params, "dm").f) <= 0.))

                E_ERROR(-39)

        else {

                P->theta = pj_param(P->params, "rtheta").f;

                P->sp0 = sin(P->phi0);

                P->cp0 = cos(P->phi0);

                P->rn = 1./ P->n;

                P->rm = 1./ P->m;

                P->two_r_n = 2. * P->rn;

                P->two_r_m = 2. * P->rm;

                P->hm = 0.5 * P->m;

                P->hn = 0.5 * P->n;

                P->fwd = s_forward;

                P->inv = s_inverse;

                P->es = 0.;

        }

ENDENTRY(P)