Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / nan-2.5.5 / trimean.m

diff --git a/octave_packages/nan-2.5.5/trimean.m b/octave_packages/nan-2.5.5/trimean.m
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+++ b/octave_packages/nan-2.5.5/trimean.m
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+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;
+