Where's the inverse of Math.tanh in the math libraries?

Question

y = Math.Tanh(x) is the hyperbolic tangent of x. But I need f(y) = x. For the regular tangent there\'s Arctan, but where\'s Arctanh?

Answer 1

Why don't you implement one by yourself? You can find the equation e.g. here and tt's not that difficult:

public static class MyMath
{
    public static double Arctanh(double x)
    {
        if (Math.Abs(x) > 1)
            throw new ArgumentException("x");

        return 0.5 * Math.Log((1 + x) / (1 - x));
    }
}