--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/scripts/control/base/tzero2.m	Fri Jan 14 04:28:06 2000 +0000
@@ -0,0 +1,66 @@
+## Copyright (C) 1993 Auburn University.  All rights reserved.
+##
+## This file is part of Octave.
+##
+## Octave is free software; you can redistribute it and/or modify it
+## under the terms of the GNU General Public License as published by the
+## Free Software Foundation; either version 2, or (at your option) any
+## later version.
+##
+## Octave is distributed in the hope that it will be useful, but WITHOUT
+## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+## FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+## for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with Octave; see the file COPYING.  If not, write to the Free
+## Software Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {@var{zr} =} tzero2 (@var{a}, @var{b}, @var{c}, @var{d}, @var{bal})
+## Compute the transmission zeros of a, b, c, d.
+##
+## bal = balancing option (see balance); default is "B".
+##
+## Needs to incorporate @code{mvzero} algorithm to isolate finite zeros; use
+## @code{tzero} instead.
+## @end deftypefn
+
+## Author: A. S. Hodel <a.s.hodel@eng.auburn.edu>
+## Created: August 1993
+
+function zr = tzero2 (a, b, c, d, bal)
+
+  if (nargin == 4)
+    bal = "B";
+  elseif (nargin != 5)
+    error ("tzero: invalid number of arguments");
+  endif
+
+  [n, m, p] = abcddim (a, b, c, d);
+
+  if (n > 0 && m > 0 && p > 0)
+    if (m != p)
+      fprintf (stderr, "tzero: number of inputs,outputs differ.  squaring up");
+      if (p > m)
+        fprintf (stderr, "       by padding b and d with zeros.");
+        b = [b, (zeros (n, p-m))];
+        d = [d, (zeros (p, p-m))];
+        m = p;
+      else
+        fprintf (stderr, "       by padding c and d with zeros.");
+        c = [c; (zeros (m-p, n))];
+        d = [d; (zeros (m-p, m))];
+        p = m;
+      endif
+      fprintf (stderr, "This is a kludge.  Try again with SISO system.");
+    endif
+    ab = [-a, -b; c, d];
+    bb = [(eye (n)), (zeros (n, m)); (zeros (p, n)), (zeros (p, m))];
+    [ab,bb] = balance (ab, bb);
+    zr = -qz (ab, bb);
+  else
+    error ("tzero: a, b, c, d not compatible.  exiting");
+  endif
+
+endfunction