--- a/scripts/control/tzero.m
+++ b/scripts/control/tzero.m
@@ -1,4 +1,4 @@
-# Copyright (C) 1993 John W. Eaton
+# Copyright (C) 1993, 1994 John W. Eaton
 # 
 # This file is part of Octave.
 # 
@@ -31,33 +31,33 @@
   if (nargin == 4)
     bal = "B";
   elseif (nargin != 5)
-    error ("tzero: illegal number of arguments");
+    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");
+      warning ("tzero: number of inputs,outputs differ.  squaring up");
       if (p > m)
-	fprintf (stderr, "       by padding b and d with zeros.");
+	warning ("       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.");
+	warning ("       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.");
+      warning ("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 = -qzval (ab, bb);
   else
-    error ("tzero: a, b, c, d not compatible.  exiting");
+    error ("tzero: a, b, c, d not compatible");
   endif
 
 endfunction