Re: Request for Matlab output

[Lukas Reichlin]

On 29.10.2015, at 18:50, Lukas Reichlin <address@hidden> wrote:
> 
>> 
>> On 29.10.2015, at 12:36, Lukas Reichlin <address@hidden> wrote:
>> 
>> Dear Octave community,
>> 
>> In order to improve error handling in the control package, I would like to 
>> know what Matlab’s output/error message looks like for each of the following 
>> three lines of code:
>> 
>> dss (1, 2, 3, 4, 0)
>> 
>> feedback (tf (1), tf (-1))
>> 
>> feedback (ss (1), ss (-1))
>> 
>> Could someone with access to Matlab and its Control System Toolbox please 
>> send me the resulting text output?
>> 
>> Thanks in advance,
>> Lukas
>> 
>> 
> 
> Gentlemen, thank you very much for your help! I’ve just pushed a file 
> containing my conclusions:
> 
> http://sourceforge.net/p/octave/control/ci/default/tree/devel/algebraic_loops.m
> 
> Best regards,
> Lukas

May I ask you for another test in Matlab?


e = zeros (2, 2);
a = [-1, 1; 1, -1];
b = [1; 0];
c = [1, 0];
d = 0;
sys = dss (a, b, c, d, e)
G = tf (sys)
H = zpk (sys)


I think that descriptor systems with all-zero E matrix and non-invertible A 
matrix are invalid. Now I wonder whether Matlab accepts those systems at all or 
only returns NaN’s later on.

Best regards,
Lukas