From bug-octave-request at bevo dot che dot wisc dot edu Mon Dec 15 05:49:30 2003
Subject: zp2sys and bode
From: Gabriele Pannocchia <g dot pannocchia at ing dot unipi dot it>
To: "Giovanni Visciano" <giovannivisciano at virgilio dot it>
Cc: bug-octave at bevo dot che dot wisc dot edu
Date: Mon, 15 Dec 2003 12:52:19 +0100

Hi,

I think the error is generated by line 74 of zp2ss.m.
Here is my fix proposal.

--- /usr/share/octave/2.1.50/m/control/system/zp2ss.m	Mon Sep 22 18:06:43 2003
+++ zp2ss.m	Mon Dec 15 12:43:49 2003
 at @ -71,7 +71,7 @@
     warning("zp2ss: k is complex")
   endif
 
-  zpsys = ss2sys([],[],[],k);
+  zpsys = ss2sys(zeros(0,0),zeros(0,1),zeros(1,0),k);
 
   ## Find the number of zeros and the number of poles
   nzer=length(zer);



The reason for this fix is that a pure gain system (as it is meant to be
defined in line 74) should have 0 states but still 1 input and 1 output. Hence
its state-space matrices should be:
A = zeros(0,0);
B = zeros(0,1);
C = zeros(1,0);
D = k;

Cheers,
	Gabriele

 > > bode (zp2sys ([],[0],1))
 > error: number of columns must match (2 != 1)
 > error: evaluating assignment expression near line 97, column 7
 > error: evaluating if command near line 71, column 3
 > error: called from `sysgroup' in file `/home/gio/Octave-2.1.50/share/octave/2.1.50/m/control/system/sysgroup.m'
 > error: evaluating assignment expression near line 96, column 9
 > error: evaluating if command near line 65, column 3
 > error: called from `sysmult' in file `/home/gio/Octave-2.1.50/share/octave/2.1.50/m/control/system/sysmult.m'
 > error: evaluating assignment expression near line 146, column 11
 > error: evaluating while command near line 95, column 3
 > error: called from `zp2ss' in file `/home/gio/Octave-2.1.50/share/octave/2.1.50/m/control/system/zp2ss.m'
 > error: evaluating if command near line 109, column 5
 > error: evaluating if command near line 107, column 3
 > error: called from `sysupdate' in file `/home/gio/Octave-2.1.50/share/octave/2.1.50/m/control/system/sysupdate.m'
 > error: evaluating assignment expression near line 153, column 9
 > error: evaluating if command near line 152, column 3
 > error: called from `sysgetsignals' in file `/home/gio/Octave-2.1.50/share/octave/2.1.50/m/control/system/sysgetsignals.m'
 > error: called from `bode' in file `/home/gio/Octave-2.1.50/share/octave/2.1.50/m/control/base/bode.m'



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