1 28994509 2004-04-21 devnull #include <u.h>
 2 28994509 2004-04-21 devnull #include <libc.h>
 3 28994509 2004-04-21 devnull #include "map.h"
 4 28994509 2004-04-21 devnull 
 5 28994509 2004-04-21 devnull static int
 6 28994509 2004-04-21 devnull Xlagrange(struct place *place, double *x, double *y)
 7 28994509 2004-04-21 devnull {
 8 28994509 2004-04-21 devnull 	double z1,z2;
 9 28994509 2004-04-21 devnull 	double w1,w2,t1,t2;
10 28994509 2004-04-21 devnull 	struct place p;
11 28994509 2004-04-21 devnull 	copyplace(place,&p);
12 28994509 2004-04-21 devnull 	if(place->nlat.l<0) {
13 28994509 2004-04-21 devnull 		p.nlat.l = -p.nlat.l;
14 28994509 2004-04-21 devnull 		p.nlat.s = -p.nlat.s;
15 28994509 2004-04-21 devnull 	}
16 28994509 2004-04-21 devnull 	Xstereographic(&p,&z1,&z2);
17 28994509 2004-04-21 devnull 	csqrt(-z2/2,z1/2,&w1,&w2);
18 28994509 2004-04-21 devnull 	cdiv(w1-1,w2,w1+1,w2,&t1,&t2);
19 28994509 2004-04-21 devnull 	*y = -t1;
20 28994509 2004-04-21 devnull 	*x = t2;
21 28994509 2004-04-21 devnull 	if(place->nlat.l<0)
22 28994509 2004-04-21 devnull 		*y = -*y;
23 28994509 2004-04-21 devnull 	return(1);
24 28994509 2004-04-21 devnull }
25 28994509 2004-04-21 devnull 
26 28994509 2004-04-21 devnull proj
27 28994509 2004-04-21 devnull lagrange(void)
28 28994509 2004-04-21 devnull {
29 28994509 2004-04-21 devnull 	return(Xlagrange);
30 28994509 2004-04-21 devnull }