added hanning.m from fieldtrip

hanning.m

@@ -0,0 +1,66 @@
+function [tap] = hanning(n, str)
+
+%HANNING   Hanning window.
+%   HANNING(N) returns the N-point symmetric Hanning window in a column
+%   vector.  Note that the first and last zero-weighted window samples
+%   are not included.
+%
+%   HANNING(N,'symmetric') returns the same result as HANNING(N).
+%
+%   HANNING(N,'periodic') returns the N-point periodic Hanning window,
+%   and includes the first zero-weighted window sample.
+%
+%   NOTE: Use the HANN function to get a Hanning window which has the 
+%          first and last zero-weighted samples. 
+%
+%   See also BARTLETT, BLACKMAN, BOXCAR, CHEBWIN, HAMMING, HANN, KAISER
+%   and TRIANG.
+%   
+%   This is a drop-in replacement to bypass the signal processing toolbox
+
+% Copyright (c) 2010, Jan-Mathijs Schoffelen, DCCN Nijmegen
+%
+% This file is part of FieldTrip, see http://www.ru.nl/neuroimaging/fieldtrip
+% for the documentation and details.
+%
+%    FieldTrip 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.
+%
+%    FieldTrip 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 FieldTrip. If not, see <http://www.gnu.org/licenses/>.
+%
+% $Id: hanning.m 8776 2013-11-14 09:04:48Z roboos $
+
+if nargin==1,
+  str = 'symmetric';
+end
+
+switch str,
+case 'periodic'
+   % Includes the first zero sample
+   tap = [0; hanningX(n-1)];
+case 'symmetric'
+   % Does not include the first and last zero sample
+   tap = hanningX(n);
+end
+
+function tap = hanningX(n)
+
+% compute taper
+N   = n+1;
+tap = 0.5*(1-cos((2*pi*(1:n))./N))';
+
+% make symmetric
+halfn = floor(n/2);
+tap( (n+1-halfn):n ) = flipud(tap(1:halfn));
+
+
+
+