[Octave-bug-tracker] [bug #55670] control pkg : peace of code works in 4.4.1 fine, and in 5.0.91 with error

[Stephan Gebauer]

URL:
  <https://savannah.gnu.org/bugs/?55670>

                 Summary: control pkg : peace of code works in 4.4.1 fine, and
in 5.0.91 with error
                 Project: GNU Octave
            Submitted by: stephan_ii
            Submitted on: Thu 07 Feb 2019 11:28:21 PM UTC
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Regression
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 5.0.91
        Operating System: Microsoft Windows

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Details:

Hi,

have a small peace of code, doesn't work anymore
with test Octave 5.0.91.
regarding the control package.




Kp = 350;
Ki = 300;
Kd = 50;
s = tf('s');
P = 1/(s^2 + 10*s + 20);
C = pid(Kp,Ki,Kd); % generate a pid cotroller

T = feedback(C*P,1);
figure(1);
step(P);
t = 0:0.01:2;
figure(2);
step(T,t);



this code cause this error messagein Octave 5.0.91:

error: 'nfields2' undefined near line 34 column 9
error: called from
    __lti_group__ at line 34 column 5
    __sys_group__ at line 39 column 14
    mtimes at line 57 column 7
    mpower at line 62 column 12
    testcase at line 5 column 3

it's the line:

P = 1/(s^2 + 10*s + 20);

Hope report ist helpfull

regards 

 Stephan







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