Derivative of Hyperbolic Secant Function

Theorem

 * $D_z \left({\operatorname{sech} z}\right) = -\operatorname{sech} z \ \tanh z$

where $\tanh$ is the hyperbolic tangent and $\operatorname{sech}$ is the hyperbolic secant.

Also see

 * Derivative of Hyperbolic Sine Function
 * Derivative of Hyperbolic Cosine Function