Definition:Inverse Hyperbolic Secant/Complex/Definition 1

Definition
The inverse hyperbolic secant is a multifunction defined as:


 * $\forall z \in \C_{\ne 0}: \operatorname{sech}^{-1} \left({z}\right) := \left\{{w \in \C: z = \operatorname{sech} \left({w}\right)}\right\}$

where $\operatorname{sech} \left({w}\right)$ is the hyperbolic secant function.

Also see

 * Equivalence of Definitions of Complex Inverse Hyperbolic Secant