Definition:Inverse Secant/Complex/Definition 1

Definition
Let $z \in \C_{\ne 0}$ be a non-zero complex number.

The inverse secant of $z$ is the multifunction defined as:
 * $\sec^{-1} \left({z}\right) := \left\{{w \in \C: \sec \left({w}\right) = z}\right\}$

where $\sec \left({w}\right)$ is the secant of $w$.

Also see

 * Equivalence of Definitions of Complex Inverse Secant Function


 * Definition:Complex Arcsecant