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Automatically retrieving some elements from a list

  • To: mathgroup at smc.vnet.net
  • Subject: [mg128972] Automatically retrieving some elements from a list
  • From: "Eduardo M. A. M. Mendes" <emammendes at gmail.com>
  • Date: Thu, 6 Dec 2012 04:58:53 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • Delivered-to: l-mathgroup@wolfram.com
  • Delivered-to: mathgroup-newout@smc.vnet.net
  • Delivered-to: mathgroup-newsend@smc.vnet.net

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




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