Date: Dec 6, 2012 4:56 AM
Author: emammendes@gmail.com
Subject: Automatically retrieving some elements from a list

Hello

I wonder whether someone could help to understand what is behind Mathematica syntax.  Here is an example:

Control`ZeroPoleGainModel[TransferFunctionModel[s+1,s]]

Control`ZeroPoleGainModel[{{{{-1}}},{},{{1}}},s]

I need to extract some values of it so that the output is

{{-1},{},{1}}


Control`ZeroPoleGainModel[TransferFunctionModel[{{2/(1+s^2),s/(s-1)}},s]]
Control`ZeroPoleGainModel[{{{{},{0}}},{{{-I,I},{1}}},{{2,1}}},s]

The same thing but the output should be

{{{},{0}},{{-l,I},{1}},{2,1}}

Can a function be written to accomplish the above outputs automatically?

BTW, is there a command to see all the functions under Control`?

Many thanks

Ed