ctrigonometry

Convert from atan2 to atan

So I saw the post asking how to convert from atan to atan2. But I haven't seen the reverse. So how would one convert from atan2 to atan? Any help is much appreciated!

I am actually extremely surprised that I could not find this question anywhere on stack overflow (my searching skills may be limited lol). I want to go this route since atan2 seems more numerically stable than atan (but I may be wrong).

Solution

  • You can do the opposite from what was done in this question.

    double myatan(double y, double x)
{
    double pi = 3.14159265358979323846;
    if (x >= 0)
        return atan2(y, x);
    else if (y >= 0)
        return atan2(y, x) - pi;
    else
        return atan2(y, x) + pi;
}