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+++ b/scripts/control/system/is_signal_list.m
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+## Copyright (C) 1996, 1998, 2000 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, 675 Mass Ave, Cambridge, MA 02139, USA.
+
+## function flg = is_signal_list (mylist)
+## returns true if mylist is a list of individual strings.
+
+function flg = is_signal_list(mylist)
+
+  flg = is_list(mylist);
+
+  if (flg)
+    for ii = 1:length (mylist)
+      if (! (isstr (nth (mylist,ii)) & rows (nth (mylist,ii)) == 1))
+	flg = 0;
+      endif
+    endfor
+  endif
+
+endfunction