Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / nnet-0.1.13 / __dradbas.m

diff --git a/octave_packages/nnet-0.1.13/__dradbas.m b/octave_packages/nnet-0.1.13/__dradbas.m
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+## Copyright (C) 2010 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} {} __dradbas (@var{n})
+## First derivative of the radial basis transfer function.
+##
+## @code{__dradbas(n) = exp(-n^2)*-2*x}
+##
+## @end deftypefn
+
+## Author: Michel D. Schmid
+
+
+function retval = __dradbas (n)
+
+  if (nargin != 1)
+    print_usage ();
+  else
+    retval = exp (-n^2)*(-2)*x;
+    # the derivative of exp(-n^2) must be calculated
+    # with help of the chain-rule!
+    # d/dx of e^x = e^x
+    # d/dx of -x^2 = -2x
+    # now calculate the product of both
+  endif
+endfunction
+
+
+#%!assert (radbas (3), exp (-3^2));