/usr/share/octave/packages/nan-2.8.1/trimean.m is in octave-nan 2.8.1-1ubuntu2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 | 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;
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