Definition:Inverse Hyperbolic Cotangent/Complex/Definition 2

Definition
The inverse hyperbolic cotangent is a multifunction defined as:


 * $\forall x \in \C: \coth^{-1} \left({x}\right) = \dfrac 1 2 \ln \left({\dfrac {x + 1} {x - 1} }\right)$

where $\ln$ denotes the complex natural logarithm considered as a multifunction.