Re: problem with the bode function - solved

[Lukas Reichlin]

On 07.12.2011, at 15:42, Lukas Reichlin wrote:

> On 07.12.2011, at 14:11, Laurent Tissier wrote:
> 
>> Hello,
>> 
>> yesterday I have updated the control toolbox (ver 2.2.2) and now the 
>> following command  fails:
>> 
>> H=tf([1 0 1],[1 1 1]);
>> bode(H)
>> 
>> I work under ubuntu 10.10 with octave 3.4.
> 
> Thanks for your report. A few observations:
> - The problem is also present with control-2.2.1.  --> not related to version 
> 2.2.2
> - [mag, pha, w] = bode (H) doesn't hang ---> looks like a plotting problem
> - both Fltk and Gnuplot graphics backends are affected
> - H=tf([1 1 1],[1 1 1]) gets plotted ---> The zero for s^1 in the numerator 
> seems to cause the problem
> - H = tf (1, [1, 0, 1]) hangs too ---> there must be a problem with complex 
> conjugate pole or zero pairs when their real part is 0.
> - Plotting mag, pha and w from point 2 works ---> hmm…
> - Commenting out the two 'axis' commands in bode.m gets your example working
> - The variable ax_vec_mag contains infs and nans when octave hangs --> I'll 
> take care of __axis_limits__.m
> 
> I'll try to fix this and release control-2.2.3.
> 
> Regards,
> Lukas

I solved the problem for bode, bodemag, sigma and nichols. I'll release 
control-2.2.3 shortly.

Regards,
Lukas