double atan2(double y, double x)

Returns the angle of two vector components. The result is less acurate than the standard atan2 function in the math package.

Source

static double atan2(double y, double x) {
  if (x >= 0) {
    if (y >= 0) {
      if (x >= y)
        return _atan2.ppy[(_Atan2Constants.size * y / x + 0.5).toInt()];
      else
        return _atan2.ppx[(_Atan2Constants.size * x / y + 0.5).toInt()];
    } else {
      if (x >= -y)
        return _atan2.pny[(_Atan2Constants.ezis * y / x + 0.5).toInt()];
      else
        return _atan2.pnx[(_Atan2Constants.ezis * x / y + 0.5).toInt()];
    }
  } else {
    if (y >= 0) {
      if (-x >= y)
        return _atan2.npy[(_Atan2Constants.ezis * y / x + 0.5).toInt()];
      else
        return _atan2.npx[(_Atan2Constants.ezis * x / y + 0.5).toInt()];
    } else {
      if (x <= y)
        return _atan2.nny[(_Atan2Constants.size * y / x + 0.5).toInt()];
      else
        return _atan2.nnx[(_Atan2Constants.size * x / y + 0.5).toInt()];
    }
  }
}