/Proj4/PJ_ocea.c

 1#ifndef lint
 2static const char SCCSID[]="@(#)PJ_ocea.c	4.1	94/02/15	GIE	REL";
 3#endif
 4#define PROJ_PARMS__ \
 5	double	rok; \
 6	double	rtk; \
 7	double	sinphi; \
 8	double	cosphi; \
 9	double	singam; \
10	double	cosgam;
11#define PJ_LIB__
12#include	"projects.h"
13PROJ_HEAD(ocea, "Oblique Cylindrical Equal Area") "\n\tCyl, Sph"
14	"lonc= alpha= or\n\tlat_1= lat_2= lon_1= lon_2=";
15FORWARD(s_forward); /* spheroid */
16	double t;
17
18	xy.y = sin(lp.lam);
19/*
20	xy.x = atan2((tan(lp.phi) * P->cosphi + P->sinphi * xy.y) , cos(lp.lam));
21*/
22	t = cos(lp.lam);
23	xy.x = atan((tan(lp.phi) * P->cosphi + P->sinphi * xy.y) / t);
24	if (t < 0.)
25		xy.x += PI;
26	xy.x *= P->rtk;
27	xy.y = P->rok * (P->sinphi * sin(lp.phi) - P->cosphi * cos(lp.phi) * xy.y);
28	return (xy);
29}
30INVERSE(s_inverse); /* spheroid */
31	double t, s;
32
33	xy.y /= P->rok;
34	xy.x /= P->rtk;
35	t = sqrt(1. - xy.y * xy.y);
36	lp.phi = asin(xy.y * P->sinphi + t * P->cosphi * (s = sin(xy.x)));
37	lp.lam = atan2(t * P->sinphi * s - xy.y * P->cosphi,
38		t * cos(xy.x));
39	return (lp);
40}
41FREEUP; if (P) pj_dalloc(P); }
42ENTRY0(ocea)
43	double phi_0=0.0, phi_1, phi_2, lam_1, lam_2, lonz, alpha;
44
45	P->rok = P->a / P->k0;
46	P->rtk = P->a * P->k0;
47	if ( pj_param(P->params, "talpha").i) {
48		alpha	= pj_param(P->params, "ralpha").f;
49		lonz = pj_param(P->params, "rlonc").f;
50		P->singam = atan(-cos(alpha)/(-sin(phi_0) * sin(alpha))) + lonz;
51		P->sinphi = asin(cos(phi_0) * sin(alpha));
52	} else {
53		phi_1 = pj_param(P->params, "rlat_1").f;
54		phi_2 = pj_param(P->params, "rlat_2").f;
55		lam_1 = pj_param(P->params, "rlon_1").f;
56		lam_2 = pj_param(P->params, "rlon_2").f;
57		P->singam = atan2(cos(phi_1) * sin(phi_2) * cos(lam_1) -
58			sin(phi_1) * cos(phi_2) * cos(lam_2),
59			sin(phi_1) * cos(phi_2) * sin(lam_2) -
60			cos(phi_1) * sin(phi_2) * sin(lam_1) );
61		P->sinphi = atan(-cos(P->singam - lam_1) / tan(phi_1));
62	}
63	P->lam0 = P->singam + HALFPI;
64	P->cosphi = cos(P->sinphi);
65	P->sinphi = sin(P->sinphi);
66	P->cosgam = cos(P->singam);
67	P->singam = sin(P->singam);
68	P->inv = s_inverse;
69	P->fwd = s_forward;
70	P->es = 0.;
71ENDENTRY(P)