Application: gvSIG desktop

#ifndef lint

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

#endif

#define PJ_LIB__

# include        <projects.h>

PROJ_HEAD(boggs, "Boggs Eumorphic") "\n\tPCyl., no inv., Sph.";

# define NITER        20

# define EPS        1e-7

# define ONETOL 1.000001

# define FXC        2.00276

# define FXC2        1.11072

# define FYC        0.49931

# define FYC2        1.41421356237309504880

FORWARD(s_forward); /* spheroid */

        double theta, th1, c;

        int i;

        theta = lp.phi;

        if (fabs(fabs(lp.phi) - HALFPI) < EPS)

                xy.x = 0.;

        else {

                c = sin(theta) * PI;

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

                        theta -= th1 = (theta + sin(theta) - c) /

                                (1. + cos(theta));

                        if (fabs(th1) < EPS) break;

                }

                theta *= 0.5;

                xy.x = FXC * lp.lam / (1. / cos(lp.phi) + FXC2 / cos(theta));

        }

        xy.y = FYC * (lp.phi + FYC2 * sin(theta));

        return (xy);

}

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

ENTRY0(boggs) P->es = 0.; P->fwd = s_forward; ENDENTRY(P)