Mercurial > octave-antonio
view scripts/statistics/std.m @ 245:16a24e76d6e0
[project @ 1993-12-03 02:00:15 by jwe]
author | jwe |
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date | Fri, 03 Dec 1993 02:00:15 +0000 |
parents | b4df021f796c |
children | 3470f1e25a79 |
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# Copyright (C) 1993 John W. Eaton # # This file is part of Octave. # # Octave 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, or (at your option) any # later version. # # Octave 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 Octave; see the file COPYING. If not, write to the Free # Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. function retval = std (a) # usage: std (a) # # For vector arguments, std returns the standard deviation of the # values. For matrix arguments, std returns a row vector containing # the standard deviation for each column. # # See also: mean, median if (nargin != 1) error ("usage: std (a)"); endif nr = rows (a); nc = columns (a); if (nc == 1 && nr == 1) retval = 0; elseif (nc == 1 || nr == 1) tmp = sum (a); n = length (a); retval = sqrt ((n * sumsq (a) - tmp .* tmp) / (n * (n - 1))); elseif (nr > 1 && nc > 0) tmp = sum (a); retval = sqrt ((nr * sumsq (a) - tmp .* tmp) / (nr * (nr - 1))); else error ("mean: invalid matrix argument"); endif endfunction