Application: gvSIG desktop

#ifndef lint

static const char SCCSID[]="@(#)PJ_putp2.c        4.1        94/02/15        GIE        REL";

#endif

#define PJ_LIB__

#include        <projects.h>

PROJ_HEAD(putp2, "Putnins P2") "\n\tPCyl., Sph.";

#define C_x        1.89490

#define C_y        1.71848

#define C_p 0.6141848493043784

#define EPS        1e-10

#define NITER        10

#define PI_DIV_3        1.0471975511965977

FORWARD(s_forward); /* spheroid */

        double p, c, s, V;

        int i;

        p = C_p * sin(lp.phi);

        s = lp.phi * lp.phi;

        lp.phi *= 0.615709 + s * ( 0.00909953 + s * 0.0046292 );

        for (i = NITER; i ; --i) {

                c = cos(lp.phi);

                s = sin(lp.phi);

                lp.phi -= V = (lp.phi + s * (c - 1.) - p) /

                        (1. + c * (c - 1.) - s * s);

                if (fabs(V) < EPS)

                        break;

        }

        if (!i)

                lp.phi = lp.phi < 0 ? - PI_DIV_3 : PI_DIV_3;

        xy.x = C_x * lp.lam * (cos(lp.phi) - 0.5);

        xy.y = C_y * sin(lp.phi);

        return (xy);

}

INVERSE(s_inverse); /* spheroid */

        double c;

        lp.phi = aasin(xy.y / C_y);

        lp.lam = xy.x / (C_x * ((c = cos(lp.phi)) - 0.5));

        lp.phi = aasin((lp.phi + sin(lp.phi) * (c - 1.)) / C_p);

        return (lp);

}

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

ENTRY0(putp2) P->es = 0.; P->inv = s_inverse; P->fwd = s_forward; ENDENTRY(P)