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rsc 2004-04-21 22:19:33 +00:00
parent a01e58366c
commit 28994509cc
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src/cmd/map/libmap/polyconic.c Normal file
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#include <u.h>
#include <libc.h>
#include "map.h"
int
Xpolyconic(struct place *place, double *x, double *y)
{
double r, alpha;
double lat2, lon2;
if(fabs(place->nlat.l) > .01) {
r = place->nlat.c / place->nlat.s;
alpha = place->wlon.l * place->nlat.s;
*y = place->nlat.l + r*(1 - cos(alpha));
*x = - r*sin(alpha);
} else {
lon2 = place->wlon.l * place->wlon.l;
lat2 = place->nlat.l * place->nlat.l;
*y = place->nlat.l * (1+(lon2/2)*(1-(8+lon2)*lat2/12));
*x = - place->wlon.l * (1-lat2*(3+lon2)/6);
}
return(1);
}
proj
polyconic(void)
{
return(Xpolyconic);
}