/Proj4/PJ_rpoly.c

 1#ifndef lint
 2static const char SCCSID[]="@(#)PJ_rpoly.c	4.1	94/02/15	GIE	REL";
 3#endif
 4#define PROJ_PARMS__ \
 5	double	phi1; \
 6	double	fxa; \
 7	double	fxb; \
 8	int		mode;
 9#define EPS	1e-9
10#define PJ_LIB__
11#include	"projects.h"
12PROJ_HEAD(rpoly, "Rectangular Polyconic")
13	"\n\tConic, Sph., no inv.\n\tlat_ts=";
14FORWARD(s_forward); /* spheroid */
15	double fa;
16
17	if (P->mode)
18		fa = tan(lp.lam * P->fxb) * P->fxa;
19	else
20		fa = 0.5 * lp.lam;
21	if (fabs(lp.phi) < EPS) {
22		xy.x = fa + fa;
23		xy.y = - P->phi0;
24	} else {
25		xy.y = 1. / tan(lp.phi);
26		xy.x = sin(fa = 2. * atan(fa * sin(lp.phi))) * xy.y;
27		xy.y = lp.phi - P->phi0 + (1. - cos(fa)) * xy.y;
28	}
29	return (xy);
30}
31FREEUP; if (P) pj_dalloc(P); }
32ENTRY0(rpoly)
33	if ((P->mode = (P->phi1 = fabs(pj_param(P->params, "rlat_ts").f)) > EPS)) {
34		P->fxb = 0.5 * sin(P->phi1);
35		P->fxa = 0.5 / P->fxb;
36	}
37	P->es = 0.; P->fwd = s_forward;
38ENDENTRY(P)