## Hyperbolic Secant

(sech)

Calcute implements the **hyperbolic secant** function with the *sech* function.

sech(1)
0.648054273664

It is defined as the inverse of the hyperbolic cosine function sech(x) = 1 / cosh(x) or equivalently sech(x) = 2) / (exp(x) + exp(-x)). Note that this definition refers to a multiplicative inverse; the **hyperbolic secant** is not the same as the inverse hyperbolic cosine (acosh) function.