function [S]=skewness2(X)
% skewness2 - computes skewness of a distribution
%   [S]=skewness2(X) computes row-wise skewness
% The unbiased Fisher's skewness for finite samples, a.k.a. G1, is used.
%   skewness = n/(n-1)/(n-2) * sum( ((X-mean)/std)^3 ) 
% Note: 
%   Positive skewness reflects an asymmetrical distribution with tail in positive values.
%   Standard Error of skewness for normal distribution is: SES ~ sqrt(6/n)
%   i.e. if abs(skew) > 2*SES, your data are significantly skewed (2 is the
%   T value à.05)
%   
%   See also kurtosis2

%% Copyright notice
%   --------------------------------------------------------------------
%   Copyright (C) 2018 Deltares
%       grasmeij
%
%       bart.grasmeijer@deltares.nl
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%       2600 MH Delft, The Netherlands
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%   This library 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.
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%   along with this library.  If not, see <http://www.gnu.org/licenses/>.
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%% Version <http://svnbook.red-bean.com/en/1.5/svn.advanced.props.special.keywords.html>
% Created: 23 May 2018
% Created with Matlab version: 9.3.0.713579 (R2017b)

% $Id$
% $Date$
% $Author$
% $Revision$
% $HeadURL$
% $Keywords: skewness$

if isvector(X)
    X=X(:);
end
sz=[size(X) 1 ];
n=sz(1);
if n<3
    error('Skewness needs sample of size > 2')
end
S=sum((X-repmat(mean(X),n,1)).^3);
S=S./(var(X).^1.5);
S=S.*(n/(n-1)/(n-2));
