[Octave-bug-tracker] [bug #60597] [octave forge] (signal) Bug in functions handling SOS

[Charles Praplan]

Follow-up Comment #3, bug #60597 (project octave):

No problem, I will continue editing the functions and post a new bug report
for cplxreal.

Now about the Matlab compatibility :

Return values :
---------------
I'm pretty sure that these functions return correct results what is not the
case of Matlab. See following example for which Matlab returs an incorrect
value for A2:
B0=[1 0 0 1], A0=[1 1 1], sys=tf(B0, A0), [B1,A1]=tfdata(sys,'vector'),
sos=tf2sos(B0,A0), [B2,A2]=sos2tf(sos)

Input arguments :
---------------
If it is clear that zp2sos must combine complex-conjugate poles or zeros, what
to do with real poles or zeros?
My idea was to let the user decide, therefore the additional parameter for
zp2sos . Now if Matlab compatibility is more important, we have to decide.
Perhaps not combining real values is preferable (so that it is clear, seeing
the result, that the poles or zeros are real). However the case of having
multiple real zeros or poles is less frequent, so not very important.

Which solution do you prefer?



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