--- /dev/null
+## Copyright (C) 2011 Lukas F. Reichlin
+##
+## This file is part of LTI Syncope.
+##
+## LTI Syncope 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 3 of the License, or
+## (at your option) any later version.
+##
+## LTI Syncope 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 LTI Syncope. If not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## check the feedback sign.
+
+## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
+## Created: December 2011
+## Version: 0.1
+
+function negfb = __conred_check_feedback_sign__ (fbsign, key = "feedback")
+
+ if (! ischar (fbsign))
+ error ("conred: key '%s' requires string value", key);
+ endif
+
+ switch (fbsign)
+ case "+"
+ negfb = false;
+ case "-"
+ negfb = true;
+ otherwise
+ error ("conred: key '%s' has an invalid value", key);
+ endswitch
+
+endfunction
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