From help-octave-request at bevo dot che dot wisc dot edu Mon Feb  2 11:07:26 2004
Subject: Re: rlocus and zp2sys
From: A S Hodel <hodelas at eng dot auburn dot edu>
To: Shaun Jackman <sjackman at telus dot net>
Cc: help-octave at bevo dot che dot wisc dot edu, octave-sources@bevo.che.wisc.edu
Date: Mon, 2 Feb 2004 11:06:07 -0600

On Wednesday, November 19, 2003, at 01:11 AM, Shaun Jackman wrote:

> I've upgraded to rlocus, and am trying to use it with zp2sys now. I've
> run into the following error.
>
> G_z = [];
> G_p = -2*pi * [1e3 10e3 10e3];
> G_k = 1000;
> G = zp2sys( G_z, G_p, G_k);
> rlocus( G)
>
> num = 1000
> den =
>
>    1.0000e+00   1.3195e+05   4.7374e+09   2.4805e+13
>
> 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
> `/usr/share/octave/2.1.50/m/control/system/sysgroup.m'

I'm sorry for the long delay in responding.  I've traced this problem 
to sysgroup.
The above code works on my machine now
(octave 2.1.50 on Mac OS X 10.2.8).  The problem is that the behavior 
of  grouping
empty matrices, e.g., zeros(0,1) changed since I originally wrote this 
function.
The if blocks in the patch below take care of the problem.

Please apply the following patch.

A. S. Hodel Dept. ECE, 200 Broun Hall, Auburn University AL 36849-5201
(334) 844-1854/fax(334) 844-1809, 
http://www.eng.auburn.edu/users/hodelas , hodelas at auburn dot edu

===================================================================
RCS file: RCS/sysgroup.m,v
retrieving revision 2.0
diff -c -r2.0 sysgroup.m
*** sysgroup.m	2004/02/02 15:44:58	2.0
--- sysgroup.m	2004/02/02 16:55:53
***************
*** 74,83 ****
       Bsys = nth(arglist,2);

       ## extract information from Asys, Bsys to consruct sys
-     Asys = sysupdate(Asys,"ss");
-     Bsys = sysupdate(Bsys,"ss");
       [n1,nz1,m1,p1] = sysdimensions(Asys);
       [n2,nz2,m2,p2] = sysdimensions(Bsys);
       [Aa,Ab,Ac,Ad,Atsam,An,Anz,Ast,Ain,Aout,Ayd] = sys2ss(Asys);
       [Ba,Bb,Bc,Bd,Btsam,Bn,Bnz,Bst,Bin,Bout,Byd] = sys2ss(Bsys);
       nA = An + Anz;
--- 74,85 ----
       Bsys = nth(arglist,2);

       ## extract information from Asys, Bsys to consruct sys
       [n1,nz1,m1,p1] = sysdimensions(Asys);
       [n2,nz2,m2,p2] = sysdimensions(Bsys);
+
+     Asys = sysupdate(Asys,"ss");
+     Bsys = sysupdate(Bsys,"ss");
+
       [Aa,Ab,Ac,Ad,Atsam,An,Anz,Ast,Ain,Aout,Ayd] = sys2ss(Asys);
       [Ba,Bb,Bc,Bd,Btsam,Bn,Bnz,Bst,Bin,Bout,Byd] = sys2ss(Bsys);
       nA = An + Anz;
***************
*** 93,102 ****
         error("sysgroup: Asys.tsam=%e, Bsys.tsam =%e", Atsam, Btsam);
       endif

!     A = [Aa,zeros(nA,nB); zeros(nB,nA),Ba];
!     B = [Ab,zeros(nA,m2); zeros(nB,m1),Bb];
!     C = [Ac,zeros(p1,nB); zeros(p2,nA),Bc];
!     D = [Ad,zeros(p1,m2); zeros(p2,m1),Bd];
       tsam = max(Atsam,Btsam);

       ## construct combined signal names; stnames must check for pure 
gain blocks
--- 95,142 ----
         error("sysgroup: Asys.tsam=%e, Bsys.tsam =%e", Atsam, Btsam);
       endif

!     if(nA*nB > 0)
!       A12 = zeros(nA,nB);
!     else
!       A12 = [];
!     endif
!     A = [Aa,A12; A12', Ba];
!
!     if(nA*m2 > 0)
!       B12 = zeros(nA,m2);
!     else
!       B12 = [];
!     endif
!     if(nB*m1 > 0)
!       B21 = zeros(nB,m1);
!     else
!       B21 = [];
!     endif
!     B = [Ab, B12; B21, Bb];
!
!     if(p1*nB > 0)
!       C12 = zeros(p1,nB);
!     else
!       C12 = [];
!     endif
!     if(p2*nA > 0)
!       C21 = zeros(p2,nA);
!     else
!       C21 = [];
!     endif
!     C = [Ac, C12; C21,Bc];
!
!     if(p1*m2 > 0)
!       D12 = zeros(p1,m2);
!     else
!       D12 = [];
!     endif
!     if(p2*m1 > 0)
!       D21 = zeros(p2,m1);
!     else
!       D21 = [];
!     endif
!     D = [Ad, D12; D21, Bd];
       tsam = max(Atsam,Btsam);

       ## construct combined signal names; stnames must check for pure 
gain blocks
***************
*** 139,145 ****
       ## multiple systems (or a single system); combine together one by 
one
       sys = nth(arglist,1);
       for kk=2:length(arglist)
-       printf("sysgroup: kk=%d\n",kk);
         sys = sysgroup(sys,nth(arglist,kk));
       endfor
     endif
--- 179,184 ----



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