[Octave-bug-tracker] [bug #58538] control package, step() and lsim() can't simulate complex transfer functions

[anonymous]

URL:
  <https://savannah.gnu.org/bugs/?58538>

                 Summary: control package, step() and lsim() can't simulate
complex transfer functions
                 Project: GNU Octave
            Submitted by: None
            Submitted on: Wed 10 Jun 2020 05:16:56 PM UTC
                Category: None
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Matlab Compatibility
                  Status: None
             Assigned to: None
         Originator Name: gs
        Originator Email: 
             Open/Closed: Open
                 Release: 5.2.0
         Discussion Lock: Any
        Operating System: GNU/Linux

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Details:

%Octave 5.2.1 and Control 3.2.0


pkg load control
q=tf([  -1.46668928632582  38.5234944088261  -1023.42433722006 
18055.8729050165  -275471.128598611  3680685.32154243  -40413629.6869944 
433109318.542883  -3699840188.09672  32827566143.7738  -225798332168.488 
1689921426466.71  -9494747382069.7  60613579740811.5  -278626623858487 
1.52747193482069e+15  -5.6883783399098e+15  2.69067309068308e+16 
-7.92226372994905e+16  3.25360727881732e+17  -7.2059792475876e+17 
2.61175754638012e+18  -3.8909506684981e+18  1.31637705830625e+19 
-9.12640045084024e+18  3.78290213329238e+19  1.41630594163597e+19 
5.02932079881115e+19  1.29547036349465e+20  1.05983336007477e+19 
2.43633391646665e+20  -1.31208497581345e+19  1.04713601706961e+20 
7.83465823853832e+18  ],[  1  17.1698120499521  542.934121038049 
7294.98595152311  126155.971925398  1377306.37948524  16829405.6386297 
152789570.438515  1448656865.6342  11095921096.5808  85365123037.7488 
556372911296.259  3555399791580.02  19799716986834.5  106353561602035 
506292672690482  2.29624277698132e+15  9.31618125768562e+15 
3.56349262092232e+16  1.22398996473335e+17  3.92373264437545e+17 
1.12860046096021e+18  2.99632129507514e+18  7.09934073973815e+18 
1.53176948230893e+19  2.91760427412351e+19  4.97010301791734e+19 
7.33491370510952e+19  9.42777562297368e+19  1.01604047339533e+20 
9.12510568398965e+19  6.44576522525933e+19  3.46367980244933e+19 
1.23309424846899e+19  2.4145011614912e+18  ]);
 
step(q)
%lsim(q,ones(1,1001),[0:.01:10])  %another simulator, same result

*****************************************

these workarounds work which indicate that the internal tf2ss step needs
correction:

1:
pkg load signal
[a,b,c,d] = tf2ss(q);
step(ss(a,b,c,d))

2:
only with the control pkg
step(ss(q)) 

**************************************

picture show result from Matlab 2020a, matlab can handle the tf's. Was only
possible to upload one picture.

see this thread for mote info:
https://octave.1599824.n4.nabble.com/control-package-can-t-simulate-complex-systems-td4697481.html







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File Attachments:


-------------------------------------------------------
Date: Wed 10 Jun 2020 05:16:56 PM UTC  Name: MatlabControlOutput.png  Size:
103KiB   By: None

<http://savannah.gnu.org/bugs/download.php?file_id=49236>

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