blob: 3f3b1d572da909c94572d749647f3607e8126073 [file] [log] [blame]
#include <u.h>
#include <libc.h>
#include "map.h"
struct coord center;
static int
Xelliptic(struct place *place, double *x, double *y)
{
double r1,r2;
r1 = acos(place->nlat.c*(place->wlon.c*center.c
- place->wlon.s*center.s));
r2 = acos(place->nlat.c*(place->wlon.c*center.c
+ place->wlon.s*center.s));
*x = -(r1*r1 - r2*r2)/(4*center.l);
*y = (r1*r1+r2*r2)/2 - (center.l*center.l+*x**x);
if(*y < 0)
*y = 0;
*y = sqrt(*y);
if(place->nlat.l<0)
*y = -*y;
return(1);
}
proj
elliptic(double l)
{
l = fabs(l);
if(l>89)
return(0);
if(l<1)
return(Xazequidistant);
deg2rad(l,&center);
return(Xelliptic);
}