PJ_fouc_s.c
1.04 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
#ifndef lint
static const char SCCSID[]="@(#)PJ_fouc_s.c 4.1 94/02/15 GIE REL";
#endif
#define PROJ_PARMS__ \
double n, n1;
#define PJ_LIB__
#include "projects.h"
PROJ_HEAD(fouc_s, "Foucaut Sinusoidal") "\n\tPCyl., Sph.";
#define MAX_ITER 10
#define LOOP_TOL 1e-7
FORWARD(s_forward); /* spheroid */
double t;
t = cos(lp.phi);
xy.x = lp.lam * t / (P->n + P->n1 * t);
xy.y = P->n * lp.phi + P->n1 * sin(lp.phi);
return (xy);
}
INVERSE(s_inverse); /* spheroid */
double V;
int i;
if (P->n) {
lp.phi = xy.y;
for (i = MAX_ITER; i ; --i) {
lp.phi -= V = (P->n * lp.phi + P->n1 * sin(lp.phi) - xy.y ) /
(P->n + P->n1 * cos(lp.phi));
if (fabs(V) < LOOP_TOL)
break;
}
if (!i)
lp.phi = xy.y < 0. ? -HALFPI : HALFPI;
} else
lp.phi = aasin(xy.y);
V = cos(lp.phi);
lp.lam = xy.x * (P->n + P->n1 * V) / V;
return (lp);
}
FREEUP; if (P) pj_dalloc(P); }
ENTRY0(fouc_s)
P->n = pj_param(P->params, "dn").f;
if (P->n < 0. || P->n > 1.)
E_ERROR(-99)
P->n1 = 1. - P->n;
P->es = 0;
P->inv = s_inverse;
P->fwd = s_forward;
ENDENTRY(P)