/usr/share/octave/packages/nan-3.1.4/nanstd.m is in octave-nan 3.1.4-3.
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 | function [y] = nanstd(x,FLAG,DIM)
% NANSTD same as STD but ignores NaN's.
% NANSTD is OBSOLETE; use NaN/STD instead. NANSTD is included
% to fix a bug in alternative implementations and to
% provide some compatibility.
%
% Y = nanstd(x, FLAG, [,DIM])
%
% x data
% FLAG 0: [default] normalizes with (N-1), N = sample size
% FLAG 1: normalizes with N, N = sample size
% DIM dimension
% 1 sum of columns
% 2 sum of rows
% default or []: first DIMENSION with more than 1 element
% Y resulting standard deviation
%
% see also: SUM, SUMSKIPNAN, NANSUM, STD
% $Id$
% Copyright (C) 2000-2003,2006,2008,2009,2010 by Alois Schloegl <alois.schloegl@gmail.com>
% This is part of the NaN-toolbox. For more details see
% http://pub.ist.ac.at/~schloegl/matlab/NaN/
% 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/>.
if nargin<2,
FLAG = 0;
end;
if nargin<3,
DIM = [];
end;
if isempty(FLAG),
FLAG = 0;
end;
if isempty(DIM),
DIM = find(size(x)>1,1);
if isempty(DIM), DIM=1; end;
end;
[y,n,ssq] = sumskipnan(x,DIM);
if all(ssq(:).*n(:) > 2*(y(:).^2)),
%% rounding error is neglectable
y = ssq - y.*y./n;
else
%% rounding error is not neglectable
[y,n] = sumskipnan(center(x,DIM).^2,DIM);
end;
if (FLAG==1)
y = sqrt(y./n); % normalize with N
else
% default method
y = sqrt(y./max(n-1,0)); % normalize with N-1
end;
%!assert(nanstd(0),NaN)
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