PJ_wink2.c
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#ifndef lint
static const char SCCSID[]="@(#)PJ_wink2.c 4.1 94/02/15 GIE REL";
#endif
#define PROJ_PARMS__ \
double cosphi1;
#define PJ_LIB__
# include "projects.h"
PROJ_HEAD(wink2, "Winkel II") "\n\tPCyl., Sph., no inv.\n\tlat_1=";
#define MAX_ITER 10
#define LOOP_TOL 1e-7
#define TWO_D_PI 0.636619772367581343
FORWARD(s_forward); /* spheroid */
double k, V;
int i;
xy.y = lp.phi * TWO_D_PI;
k = PI * sin(lp.phi);
lp.phi *= 1.8;
for (i = MAX_ITER; i ; --i) {
lp.phi -= V = (lp.phi + sin(lp.phi) - k) /
(1. + cos(lp.phi));
if (fabs(V) < LOOP_TOL)
break;
}
if (!i)
lp.phi = (lp.phi < 0.) ? -HALFPI : HALFPI;
else
lp.phi *= 0.5;
xy.x = 0.5 * lp.lam * (cos(lp.phi) + P->cosphi1);
xy.y = FORTPI * (sin(lp.phi) + xy.y);
return (xy);
}
FREEUP; if (P) pj_dalloc(P); }
ENTRY0(wink2)
P->cosphi1 = cos(pj_param(P->params, "rlat_1").f);
P->es = 0.; P->inv = 0; P->fwd = s_forward;
ENDENTRY(P)