25 lines
339 B
C
25 lines
339 B
C
#include <u.h>
|
|
#include <libc.h>
|
|
/*
|
|
atan2 discovers what quadrant the angle
|
|
is in and calls atan.
|
|
*/
|
|
|
|
double
|
|
atan2(double arg1, double arg2)
|
|
{
|
|
|
|
if(arg1+arg2 == arg1) {
|
|
if(arg1 >= 0)
|
|
return PIO2;
|
|
return -PIO2;
|
|
}
|
|
arg1 = atan(arg1/arg2);
|
|
if(arg2 < 0) {
|
|
if(arg1 <= 0)
|
|
return arg1 + PI;
|
|
return arg1 - PI;
|
|
}
|
|
return arg1;
|
|
}
|