Re: Control Toolbox Function : zpk

[Dmitri A. Sergatskov]

Please reply to the mailing list.

Your Fedora and octave are both old. 

If you cannot update those, my only suggestion is to 

remove octave-control rpm and install 

the control package directly from octave-forge:

octave:1> pkg install -forge control

etc...

Dmitri.

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On Wed, Mar 30, 2022 at 5:59 PM Richard Shadbolt <richard.shadbolt@btinternet.com> wrote:

Hi Dmitri,

Thanks for the reply.

I am using Fedora 34, Octave is v5.20, Control Toolbox is v3.40

Thanks and regards,

Richard.

On 30/03/2022 22:46, Dmitri A. Sergatskov wrote:

On Wed, Mar 30, 2022 at 5:14 PM Richard Shadbolt via Help-octave <help-octave@gnu.org> wrote:

Hi,

I am attempting to use the Control Toolbox function zpk which is stated
to have been implemented :

https://wiki.octave.org/wiki/index.php?title=Control_package&mobileaction=toggle_view_desktop

Yet i am obtaining the error for a basic command :

     F=zpk([], [-1 -2 -2], 2);

The error is :

     error: '__lti_input_idx__' undefined near line 80 column 24

I think i am using the correct syntax etc.m for the command. The
documentation page indicates that it may not be fully implemented.

     https://octave.sourceforge.io/control/function/zpk.html

States :

     Create transfer function model from zero-pole-gain data. This is
just a stop-gap compatibility wrapper since zpk models are not yet
implemented.

As such, can someone confirm whether the function has or has not been
implemented ?

Thanks and regards,

Richard.

Something is wrong with your octave installation. What is your OS?

How did you install  octave and control package?

The command works for me:

octave:1> pkg load control
octave:2>  F=zpk([], [-1 -2 -2], 2)

Transfer function 'F' from input 'u1' to output ...

                2          
 y1:  ---------------------
      s^3 + 5 s^2 + 8 s + 4

Continuous-time model.

Dmitri.

p.s. You probably get more attention to the problem on discourse.

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