--- /dev/null
+## Copyright (C) 2005 Michel D. Schmid <michaelschmid@users.sourceforge.net>
+##
+##
+## This program 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.
+##
+## This program 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 this program; see the file COPYING. If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {}@var{a}= purelin (@var{n})
+## @code{purelin} is a linear transfer function used
+## by neural networks
+## @end deftypefn
+
+## Author: Michel D. Schmid
+
+function a = purelin(n)
+
+ a = n;
+
+endfunction
+
+%!assert(purelin(2),2);
+%!assert(purelin(-2),-2);
+%!assert(purelin(0),0);
+
+%!error # this test must throw an error!
+%! assert(purelin(2),1);
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