[Octave-bug-tracker] [bug #40932] control package: system format affects computation of controller

[Lukas Reichlin]

Follow-up Comment #3, bug #40932 (project octave):

Thanks for your report. I can confirm the problem with file1.m on my Mac:

error: ncfsyn: 2: the Z-Riccati equation is not solved successfully
error: memory exhausted or requested size too large for range of Octave's
index type -- trying to return to prompt

The problem is line 20 in file1.m:

G=[g11 g12 g13; g21 g22 g23; g31 g32 g33];

With the current implementation of horzcat and vertcat, transfer function
interconnections are calculated in state-space, requiring several conversions
back and forth. This causes the extremely high model orders of G and Gss due
to numerical problems. The solution is described in my projects file for quite
some time:
http://sourceforge.net/p/octave/control/ci/default/tree/devel/PROJECTS
It looks like I should finally tackle this problem!


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