- `Y = sech (X)`

Compute the hyperbolic secant of each element of `X`.

This is defined as

> > `%sech(z) = 1/cosh(z)%`

See also: `asech`.

### References

- https://www.mathworks.com/help/matlab/ref/sech.html
- https://octave.sourceforge.io/octave/function/sech.html
- https://mathworld.wolfram.com/HyperbolicFunctions.html
- https://en.wikipedia.org/wiki/Hyperbolic_functions