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#define PJ_LIB__
#include <errno.h>
#include <math.h>
#include "projects.h"
PROJ_HEAD(wink2, "Winkel II") "\n\tPCyl, Sph, no inv\n\tlat_1=";
struct pj_opaque { double cosphi1; };
#define MAX_ITER 10
#define LOOP_TOL 1e-7
static XY s_forward (LP lp, PJ *P) { /* Spheroidal, forward */
XY xy = {0.0, 0.0};
double k, V;
int i;
xy.y = lp.phi * M_TWO_D_PI;
k = M_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.) ? -M_HALFPI : M_HALFPI;
else
lp.phi *= 0.5;
xy.x = 0.5 * lp.lam * (cos (lp.phi) + P->opaque->cosphi1);
xy.y = M_FORTPI * (sin (lp.phi) + xy.y);
return xy;
}
PJ *PROJECTION(wink2) {
struct pj_opaque *Q = pj_calloc (1, sizeof (struct pj_opaque));
if (0==Q)
return pj_default_destructor(P, ENOMEM);
P->opaque = Q;
P->opaque->cosphi1 = cos(pj_param(P->ctx, P->params, "rlat_1").f);
P->es = 0.;
P->inv = 0;
P->fwd = s_forward;
return P;
}
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