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Re: Book for Control 2.0.0
From: |
Lukas Reichlin |
Subject: |
Re: Book for Control 2.0.0 |
Date: |
Mon, 21 Mar 2011 17:03:47 +0100 |
On 21.03.2011, at 13:50, Richard Balogh wrote:
> It would be nice, if the examples from the above mentioned "Matlab
> Compendium"
> would work also in octave - no need to write another documentation :)
>
> I've tried first of them (page 10, p. 16 in .pdf).
>
> One issue is lack of the zpk function.
>
> Another, probably more important is that results are different:
>
> Matlab output:
>
> Transfer function: 8 / (s^2 + 30)
> A_ss_tf_ss = [ 0 -7.5000 ; 4.0000 0]
>
> Octave output:
>
> Transfer function: 8 s^2 / ( s^4 + 30 s^2 )
> A_ss_tf_ss = [ 0 1 0 0; 0 0 1 0; 0 0 0 1;
> -0 -0 -30 -0]
>
> Richard Balogh
Hi Richard,
Could you please provide the m-file that you used for the transfer function?
From the results I can't tell whether Matlab computed a minimal realization
(zero-pole cancellation at s = 0) or Octave introduced additional pairs of
zeros and poles.
ZPK models are not available yet. As a workaround, you can use
sys = tf (k*poly (z), poly (p))
as well as
p = pole (sys)
[z, k] = zero (sys)
Maybe I should write a wrapper for these commands.
Regards,
Lukas