PJ_hatano.c
1.32 KB
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#define PJ_LIB__
#include <projects.h>
PROJ_HEAD(hatano, "Hatano Asymmetrical Equal Area") "\n\tPCyl, Sph.";
#define NITER 20
#define EPS 1e-7
#define ONETOL 1.000001
#define CN 2.67595
#define CS 2.43763
#define RCN 0.37369906014686373063
#define RCS 0.41023453108141924738
#define FYCN 1.75859
#define FYCS 1.93052
#define RYCN 0.56863737426006061674
#define RYCS 0.51799515156538134803
#define FXC 0.85
#define RXC 1.17647058823529411764
FORWARD(s_forward); /* spheroid */
double th1, c;
int i;
c = sin(lp.phi) * (lp.phi < 0. ? CS : CN);
for (i = NITER; i; --i) {
lp.phi -= th1 = (lp.phi + sin(lp.phi) - c) / (1. + cos(lp.phi));
if (fabs(th1) < EPS) break;
}
xy.x = FXC * lp.lam * cos(lp.phi *= .5);
xy.y = sin(lp.phi) * (lp.phi < 0. ? FYCS : FYCN);
return (xy);
}
INVERSE(s_inverse); /* spheroid */
double th;
th = xy.y * ( xy.y < 0. ? RYCS : RYCN);
if (fabs(th) > 1.)
if (fabs(th) > ONETOL) I_ERROR
else th = th > 0. ? HALFPI : - HALFPI;
else
th = asin(th);
lp.lam = RXC * xy.x / cos(th);
th += th;
lp.phi = (th + sin(th)) * (xy.y < 0. ? RCS : RCN);
if (fabs(lp.phi) > 1.)
if (fabs(lp.phi) > ONETOL) I_ERROR
else lp.phi = lp.phi > 0. ? HALFPI : - HALFPI;
else
lp.phi = asin(lp.phi);
return (lp);
}
FREEUP; if (P) pj_dalloc(P); }
ENTRY0(hatano) P->es = 0.; P->inv = s_inverse; P->fwd = s_forward; ENDENTRY(P)