--- /dev/null
+function y=trimean(x,DIM)
+% TRIMEAN yields the weighted mean of the median and the quartiles
+% m = TRIMEAN(y).
+%
+% The trimean is m = (Q1+2*MED+Q3)/4
+% with quartile Q1 and Q3 and median MED
+%
+% N-dimensional data is supported
+%
+% REFERENCES:
+% [1] http://mathworld.wolfram.com/Trimean.html
+
+
+% 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 of the License, 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; If not, see <http://www.gnu.org/licenses/>.
+
+% $Id: trimean.m 9601 2012-02-09 14:14:36Z schloegl $
+% Copyright (C) 1996-2003,2009,2010 by Alois Schloegl <alois.schloegl@gmail.com>
+% This function is part of the NaN-toolbox
+% http://pub.ist.ac.at/~schloegl/matlab/NaN/
+
+global FLAG_NANS_OCCURED;
+
+% check dimension
+sz=size(x);
+
+% find the dimension
+if nargin==1,
+ DIM = find(size(x)>1,1);
+ if isempty(DIM), DIM=1; end;
+end;
+
+if DIM>length(sz),
+ sz = [sz,ones(1,DIM-length(sz))];
+end;
+
+D1 = prod(sz(1:DIM-1));
+D2 = sz(DIM);
+D3 = prod(sz(DIM+1:length(sz)));
+D0 = [sz(1:DIM-1),1,sz(DIM+1:length(sz))];
+y = repmat(nan,D0);
+q = repmat(nan,3,1);
+for k = 0:D1-1,
+for l = 0:D3-1,
+ xi = k + l * D1*sz(DIM) + 1 ;
+ xo = k + l * D1 + 1;
+ t = x(xi+(0:sz(DIM)-1)*D1);
+ t = sort(t(~isnan(t)));
+ t = t(:);
+ n = length(t);
+ if (n<D2)
+ FLAG_NANS_OCCURED = 1;
+ end;
+
+ % q = flix(t,x); % The following find the quartiles and median.
+ % INTERP1 is not an alternative since it fails for n<2;
+ x = n*[0.25;0.50;0.75] + [0.75;0.50;0.25];
+ d = x - floor(x); % distance to next sample
+
+ t = t(:);
+ ix = ~logical(d); % find integer indices
+ q(ix) = t(x(ix)); % put integer indices
+ ix = ~ix; % find non-integer indices
+ q(ix) = t(floor(x(ix))).*(1-d(ix)) + t(ceil(x(ix))).*d(ix);
+
+ y(xo) = (q(1) + 2*q(2) + q(3))/4;
+end;
+end;
+