# Keyboard shortcut for transfer function model symbol

I am wondering if there is any keyboard shortcut to type transfer function model symbol as in the picture below.

I would like to plot root locus of that function but I can't figure out how to type the transfer function model symbol.

• Like almost everything in Mathematica, this is a function. It's name is TransferFunctionModel and is used as TransferFunctionModel[{{{k (1 + s)}}, ((-1 + s) s) (16 + 4 s + s^2)}, s] – bill s Dec 4 '16 at 15:57
• @bill I have the feeling the OP wants to know how you get this fancy input with that scripted capital T there. The examples given in the documentation suggest that you could do something like that. Transpose can be written similarly fancy by entering esc-tr-esc after a matrix, so the suggestion might be that a similar trick is possible for a transfer function or a statespace matrix. – Sjoerd C. de Vries Dec 4 '16 at 18:46
• @Sjoerd C. de Vries, yes that is what I want. However, from the answer I there is no such a thing to do it now. – anhnha Dec 4 '16 at 22:13

## 2 Answers

Like almost everything in Mathematica, this is a function. It's name is TransferFunctionModel and is used as

TransferFunctionModel[{{{k (1 + s)}}, ((-1 + s) s) (16 + 4 s + s^2)}, s]


If you find yourself using it a lot, one thing you can do it to define your own "shortcut".

tf[f_, s_] := TransferFunctionModel[f, s];


Now you can use the tf shortcut at will:

tf[{{{k (1 + s)}}, ((-1 + s) s) (16 + 4 s + s^2)}, s]


The prefix syntax also works:

tf @@ {{{{k (1 + s)}}, ((-1 + s) s) (16 + 4 s + s^2)}, s}


as does the infix syntax:

{{{k (1 + s)}}, ((-1 + s) s) (16 + 4 s + s^2)}~tf~s

• Thanks for the shortcuts. How can you write the fraction like that? – anhnha Dec 4 '16 at 16:27
• I'm not sure I know what you mean. If you evaluate any of the above, it appears in the notebook just as in your image. – bill s Dec 4 '16 at 16:34
• I mean this fraction {{{k (1 + s)}}, ((-1 + s) s) (16 + 4 s + s^2)}. Is there a guideline about how it work? – anhnha Dec 4 '16 at 16:35
• It's in the form of a list: {{numerator polynomial}, denominator polynomial}. Look at the help file for TransferFunctionModel for a bunch of examples. If you want alternative ways to enter the fraction, check out the "Basic Math Assistant" under the Palettes menu. – bill s Dec 4 '16 at 16:40
• Thanks. I just confused about the fraction as a list. – anhnha Dec 4 '16 at 16:41

You can use evaluate in place (keyboard short cut on OSX is Cmd+Enter). Here is a short animation: