Re: question on control-1.0.11 package

[Lukas Reichlin]

If you look at the m-file [1] of tf2zp, the reason is obvious:

k = num(1) / den(1);

Because your numerator num has leading zeros, Octave calculates

k = 0 / 1

Use num = [1] and you will get the correct result.

Regards,
Lukas

[1]
http://octave.svn.sourceforge.net/viewvc/octave/trunk/octave-forge/extra/control-legacy/inst/tf2zp.m?revision=6995&view=markup

> On 4/24/10 3:40 PM, Francesco Potortì wrote:
> > > Edit: by another calculation using tf2zp the difference between  
> > > Octave
> > > and Matlab shows again. Octave returns for k = 0, while Matlab  
> > > returns
> > > for k = 100.
> >
> > I don't think that it is possible to understand what is going on  
> > without
> > code.  Can you provide an example?
>
> Sure.
>
> num = [0 0 0 100];
> den = [1 10.1 101 0];
> [z,p,k] = tf2zp(num, den);
>
> Octave gives:
>
> octave-3.2.3:7> [z,p,k] = tf2zp(num, den)
> z = [](0x1)
> p =
>
>   -5.05000 + 8.68893i
>   -5.05000 - 8.68893i
>    0.00000 + 0.00000i
>
> k = 0
>
> Matlab gives:
>
> > > [z,p,k] = tf2zp(num, den)
>
> z =
>
>    Empty matrix: 0-by-1
>
>
> p =
>
>         0
>   -5.0500 + 8.6889i
>   -5.0500 - 8.6889i
>
>
> k =
>
>    100
>
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