| gvSIG desktop 1

#ifndef lint

static const char SCCSID[]="@(#)PJ_eqdc.c        4.2        94/03/16        GIE        REL";

#endif

#define PROJ_PARMS__ \

        double phi1; \

        double phi2; \

        double n; \

        double rho; \

        double rho0; \

        double c; \

        double *en; \

        int                ellips;

#define PJ_LIB__

#include        <projects.h>

PROJ_HEAD(eqdc, "Equidistant Conic")

        "\n\tConic, Sph&Ell\n\tlat_1= lat_2=";

# define EPS10        1.e-10

FORWARD(e_forward); /* sphere & ellipsoid */

        P->rho = P->c - (P->ellips ? pj_mlfn(lp.phi, sin(lp.phi),

                cos(lp.phi), P->en) : lp.phi);

        xy.x = P->rho * sin( lp.lam *= P->n );

        xy.y = P->rho0 - P->rho * cos(lp.lam);

        return (xy);

}

INVERSE(e_inverse); /* sphere & ellipsoid */

        if ((P->rho = hypot(xy.x, xy.y = P->rho0 - xy.y)) != 0.0 ) {

                if (P->n < 0.) {

                        P->rho = -P->rho;

                        xy.x = -xy.x;

                        xy.y = -xy.y;

                }

                lp.phi = P->c - P->rho;

                if (P->ellips)

                        lp.phi = pj_inv_mlfn(lp.phi, P->es, P->en);

                lp.lam = atan2(xy.x, xy.y) / P->n;

        } else {

                lp.lam = 0.;

                lp.phi = P->n > 0. ? HALFPI : - HALFPI;

        }

        return (lp);

}

SPECIAL(fac) {

        double sinphi, cosphi;

        sinphi = sin(lp.phi);

        cosphi = cos(lp.phi);

        fac->code |= IS_ANAL_HK;

        fac->h = 1.;

        fac->k = P->n * (P->c - (P->ellips ? pj_mlfn(lp.phi, sinphi,

                cosphi, P->en) : lp.phi)) / pj_msfn(sinphi, cosphi, P->es);

}

FREEUP; if (P) { if (P->en) pj_dalloc(P->en); pj_dalloc(P); } }

ENTRY1(eqdc, en)

        double cosphi, sinphi;

        int secant;

        P->phi1 = pj_param(P->params, "rlat_1").f;

        P->phi2 = pj_param(P->params, "rlat_2").f;

        if (fabs(P->phi1 + P->phi2) < EPS10) E_ERROR(-21);

        if (!(P->en = pj_enfn(P->es)))

                E_ERROR_0;

        P->n = sinphi = sin(P->phi1);

        cosphi = cos(P->phi1);

        secant = fabs(P->phi1 - P->phi2) >= EPS10;

        if( (P->ellips = (P->es > 0.)) ) {

                double ml1, m1;

                m1 = pj_msfn(sinphi, cosphi, P->es);

                P->en = pj_enfn(P->es);

                ml1 = pj_mlfn(P->phi1, sinphi, cosphi, P->en);

                if (secant) { /* secant cone */

                        sinphi = sin(P->phi2);

                        cosphi = cos(P->phi2);

                        P->n = (m1 - pj_msfn(sinphi, cosphi, P->es)) /

                                (pj_mlfn(P->phi2, sinphi, cosphi, P->en) - ml1);

                }

                P->c = ml1 + m1 / P->n;

                P->rho0 = P->c - pj_mlfn(P->phi0, sin(P->phi0),

                        cos(P->phi0), P->en);

        } else {

                if (secant)

                        P->n = (cosphi - cos(P->phi2)) / (P->phi2 - P->phi1);

                P->c = P->phi1 + cos(P->phi1) / P->n;

                P->rho0 = P->c - P->phi0;

        }

        P->inv = e_inverse;

        P->fwd = e_forward;

        P->spc = fac;

ENDENTRY(P)