1 #include <u.h>
2 #include <libc.h>
3 #include "map.h"
4 
5 static struct coord stdpar0, stdpar1;
6 static double k;
7 static double yeq;
8 
9 static int
10 Xtrapezoidal(struct place *place, double *x, double *y)
11 {
12 	*y = yeq + place->nlat.l;
13 	*x = *y*k*place->wlon.l;
14 	return 1;
15 }
16 
17 proj
18 trapezoidal(double par0, double par1)
19 {
20 	if(fabs(fabs(par0)-fabs(par1))<.1)
21 		return rectangular(par0);
22 	deg2rad(par0,&stdpar0);
23 	deg2rad(par1,&stdpar1);
24 	if(fabs(par1-par0) < .1)
25 		k = stdpar1.s;
26 	else
27 		k = (stdpar1.c-stdpar0.c)/(stdpar0.l-stdpar1.l);
28 	yeq = -stdpar1.l - stdpar1.c/k;
29 	return Xtrapezoidal;
30 }