[Octave-bug-tracker] [bug #41353] Step&bode do not work with constant transfer functions

[anonymous]

URL:
  <http://savannah.gnu.org/bugs/?41353>

                 Summary: Step&bode do not work with constant transfer
functions
                 Project: GNU Octave
            Submitted by: None
            Submitted on: Sun 26 Jan 2014 05:42:24 PM UTC
                Category: Octave Forge Package
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: Carlos Martinez
        Originator Email: address@hidden
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 3.8.0
        Operating System: GNU/Linux

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Details:

Hello there,

I am reporting a trivial bug with step or bode. The two code portions do the
same, but due to internal representation issues the second snippet produces an
error.

Correct,

G = tf(1,[1 -1]);
C = tf([1 -1], 1);
T = G*C/(1+G*C);
step(T);
bode(T);


Whereas without factorizing the transfer function,

T = tf(1,2);
step(T);
bode(T);


produces


error: c2d: system is already discrete-time
error: called from:
error:   /home/carlosm/octave/control-2.6.1/@lti/c2d.m at line 67, column 5
error:   /home/carlosm/octave/control-2.6.1/__time_response__.m at line 111,
column 7
error:   /home/carlosm/octave/control-2.6.1/step.m at line 89, column 10


I had expected the same results as above.




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