copySign function

double copySign(double magnitude, double sign)

Returns the first argument with the sign of the second argument. A NaN sign argument is treated as positive.

• magnitude the value to return.
• sign the sign for the returned value. Returns the magnitude with the same sign as the sign argument.

Implementation

double copySign(double magnitude, double sign) {
  // The highest order bit is going to be zero if the
  // highest order bit of m and s is the same and one otherwise.
  // So (m^s) will be positive if both m and s have the same sign
  // and negative otherwise.
  /*final long m = Double.doubleToRawLongBits(magnitude); // don't care about NaN
  final long s = Double.doubleToRawLongBits(sign);
  if ((m^s) >= 0) {
      return magnitude;
  }
  return -magnitude; // flip sign*/
  if (sign == 0.0 || sign.isNaN || magnitude.sign == sign.sign) {
    return magnitude;
  }
  return -magnitude; // flip sign
}