Definition:Inverse Secant/Complex/Arcsecant

Definition
The principal branch of the complex inverse secant function is defined as:
 * $\operatorname{arcsec} \left({z}\right) = \dfrac 1 i \operatorname{Ln} \left({\dfrac {1 + \sqrt{1 - z^2} } z}\right)$

where:
 * $\operatorname{Ln}$ denotes the principal branch of the complex natural logarithm
 * $\sqrt{1 - z^2}$ denotes the principal square root of $1 - z^2$.

Also see

 * Derivation of Complex Arcsecant from Inverse Secant Multifunction