Arctanh
From specialfunctionswiki
The inverse hyperbolic tangent function $\mathrm{arctanh}$ is the inverse function of the hyperbolic tangent function. It may be defined by $$\mathrm{arctanh}(z) = \dfrac{\log(1+z)}{2} - \dfrac{\log(1-z)}{2},$$ where $\log$ denotes the logarithm.
Plot of $\mathrm{arctanh}$ on $(-1,1)$.
Domain coloring of analytic continuation of $\mathrm{arctanh}$.
Properties
Derivative of arctanh
Derivative of Legendre chi
