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## Re: SIMO systems

 From: A S Hodel Subject: Re: SIMO systems Date: Wed, 6 Aug 2003 11:31:05 -0500

That's a hole in the controls toolbox. When my students and I wrote it (pre-MATLAB 5) we only did SISO tf/zp format. ss will let you do MIMO/SIMO format. This could probably use some work to select a better data format (perhaps set up a new user-defined data type) and rewrite the toolbox to allow more flexibility like that.
```
| { ideas } | >> | time available |

so for now it's still just ideas.

On Thursday, July 31, 2003, at 01:50 AM, Geraint Paul Bevan wrote:

```
```Mauro Casse wrote:
```
Hi, I can't find how to do this, I must obtain the space state representation of the followig transfer function with single input and two outputs
```                    1                [  1  ]
G(s) = ------------------- * |       | (this is a column vector)
s^2+5*s+1       [ s+1]
the following commands works in Matlab, but octave return this error
octave:26> num = [ 0 1; 1 1];
octave:27> den = [ 1 5 6 ];
octave:28> [ A, B, C, D] = tf2ss(num,den)
error: num(2x2) must be a vector
error: evaluating if command near line 51, column 3
error: called from /usr/local/share/octave/2.1.50/m/control/sys
```
```

```
tf2ss requires the numerator to have only one column, i.e. it only works with simple gains in the numerator. You can create the state space representation manually however:
```

octave> [A,B,C1,D1] = tf2ss (    1  , [1,5,6] );
octave> [A,B,C2,D2] = tf2ss ( [1,1] , [1,5,6] );
octave> C = [C1;C2];
octave> D = [D1;D2];
octave> A,B,C,D
A =

0   1
-6  -5

B =

0
1

C =

1  0
1  1

D =

0
0

--
Geraint Bevan
Department of Mechanical Engineering
University of Glasgow
Tel: +44 (0)141 330 5917

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```
A. S. Hodel, Assoc. Prof, Dept. Elect & Comp Eng, Auburn University, AL 36849-5201
```(334) 844-1854 200 Broun Hall address@hidden
Auburn web page: http://www.eng.auburn.edu/~scotte
Personal web page: http://homepage.mac.com/hodelas

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Octave is freely available under the terms of the GNU GPL.

Octave's home on the web:  http://www.octave.org
How to fund new projects:  http://www.octave.org/funding.html
Subscription information:  http://www.octave.org/archive.html
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```

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