public static double atanh(double a) {final double mult;if (Double.doubleToRawLongBits(a) < 0) {a = Math.abs(a);mult = -0.5d;} else {mult = 0.5d;}return mult * Math.log((1.0d + a) / (1.0d - a));}
public static double Atanh(double a){double mult;if (J2N.BitConversion.DoubleToRawInt64Bits(a) < 0){a = Math.Abs(a);mult = -0.5d;}else{mult = 0.5d;}return mult * Math.Log((1.0d + a) / (1.0d - a));}