Subversion Repositories planix.SVN

#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;
}