Re: Control Toolbox Function : zpk

On Wed, Mar 30, 2022 at 5:14 PM Richard Shadbolt via Help-octave <
[email protected]> 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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