Requires implementation of Octave function `stepinfo`

see:
https://wiki.octave.org/Control_package#Linear_Analysis

see Matlab docu for `stepinfo`:
https://www.mathworks.com/help/control/ref/stepinfo.html

someone made a proposal for it in 2015:
https://lists.gnu.org/archive/html/help-octave/2015-02/msg00035.html