Application: gvSIG desktop

#ifndef lint

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

#endif

#define PJ_LIB__

#include        <projects.h>

PROJ_HEAD(merc, "Mercator") "\n\tCyl, Sph&Ell\n\tlat_ts=";

#define EPS10 1.e-10

FORWARD(e_forward); /* ellipsoid */

        if (fabs(fabs(lp.phi) - HALFPI) <= EPS10) F_ERROR;

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

        xy.y = - P->k0 * log(pj_tsfn(lp.phi, sin(lp.phi), P->e));

        return (xy);

}

FORWARD(s_forward); /* spheroid */

        if (fabs(fabs(lp.phi) - HALFPI) <= EPS10) F_ERROR;

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

        xy.y = P->k0 * log(tan(FORTPI + .5 * lp.phi));

        return (xy);

}

INVERSE(e_inverse); /* ellipsoid */

        if ((lp.phi = pj_phi2(exp(- xy.y / P->k0), P->e)) == HUGE_VAL) I_ERROR;

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

        return (lp);

}

INVERSE(s_inverse); /* spheroid */

        lp.phi = HALFPI - 2. * atan(exp(-xy.y / P->k0));

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

        return (lp);

}

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

ENTRY0(merc)

        double phits=0.0;

        int is_phits;

        if( (is_phits = pj_param(P->params, "tlat_ts").i) ) {

                phits = fabs(pj_param(P->params, "rlat_ts").f);

                if (phits >= HALFPI) E_ERROR(-24);

        }

        if (P->es) { /* ellipsoid */

                if (is_phits)

                        P->k0 = pj_msfn(sin(phits), cos(phits), P->es);

                P->inv = e_inverse;

                P->fwd = e_forward;

        } else { /* sphere */

                if (is_phits)

                        P->k0 = cos(phits);

                P->inv = s_inverse;

                P->fwd = s_forward;

        }

ENDENTRY(P)