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
|
## Copyright (C) 1996 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, 59 Temple Place - Suite 330, Boston, MA
## 02111-1307, USA.
## 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
## Author: jwe
function retval = std (a)
if (nargin != 1)
usage ("std (a)");
endif
nr = rows (a);
nc = columns (a);
if (nc == 1 && nr == 1)
retval = 0;
elseif (nc == 1 || nr == 1)
n = length (a);
retval = sqrt (sumsq (a - mean (a)) / (n - 1));
elseif (nr > 1 && nc > 0)
retval = sqrt (sumsq (a - ones (nr, 1) * mean (a)) / (nr - 1));
else
error ("std: invalid matrix argument");
endif
endfunction
|
