/usr/share/octave/packages/3.2/nan-2.4.4/sem.m is in octave-nan 2.4.4-1.
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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 | function [SE,M]=sem(x,DIM, W)
% SEM calculates the standard error of the mean
%
% [SE,M] = SEM(x [, DIM [,W]])
% calculates the standard error (SE) in dimension DIM
% the default DIM is the first non-single dimension
% M returns the mean.
% Can deal with complex data, too.
%
% DIM dimension
% 1: SEM of columns
% 2: SEM of rows
% N: SEM of N-th dimension
% default or []: first DIMENSION, with more than 1 element
% W weights to compute weighted mean and s.d. (default: [])
% if W=[], all weights are 1.
% number of elements in W must match size(x,DIM)
%
% features:
% - can deal with NaN's (missing values)
% - weighting of data
% - dimension argument
% - compatible to Matlab and Octave
%
% see also: SUMSKIPNAN, MEAN, VAR, STD
% 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 3 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/>.
% Copyright (C) 2000-2003,2008,2009 by Alois Schloegl <alois.schloegl@gmail.com>
% $Id: sem.m 8223 2011-04-20 09:16:06Z schloegl $
% This function is part of the NaN-toolbox
% http://pub.ist.ac.at/~schloegl/matlab/NaN/
if nargin>2,
[S,N,SSQ] = sumskipnan(x,DIM,W);
elseif nargin>1,
[S,N,SSQ] = sumskipnan(x,DIM);
else
[S,N,SSQ] = sumskipnan(x);
end
M = S./N;
SE = (SSQ.*N - real(S).^2 - imag(S).^2)./(N.*N.*(N-1));
SE(SE<=0) = 0; % prevent negative value caused by round-off error
SE = sqrt(real(SE));
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