Mercurial > hg > octave-lyh

annotate scripts/statistics/base/std.m @ 3200:781c930425fd

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
[project @ 1998-10-29 05:23:08 by jwe]
author jwe
date Thu, 29 Oct 1998 05:23:09 +0000
parents
children 0748b03c3510
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
3200
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
1 ## Copyright (C) 1996, 1997 John W. Eaton
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
2 ##
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
3 ## This file is part of Octave.
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
4 ##
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
5 ## Octave is free software; you can redistribute it and/or modify it
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
6 ## under the terms of the GNU General Public License as published by
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
7 ## the Free Software Foundation; either version 2, or (at your option)
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
8 ## any later version.
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
9 ##
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
10 ## Octave is distributed in the hope that it will be useful, but
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
11 ## WITHOUT ANY WARRANTY; without even the implied warranty of
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
13 ## General Public License for more details.
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
14 ##
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
15 ## You should have received a copy of the GNU General Public License
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
16 ## along with Octave; see the file COPYING. If not, write to the Free
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
17 ## Software Foundation, 59 Temple Place - Suite 330, Boston, MA
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
18 ## 02111-1307, USA.
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
19
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
20 ## usage: std (a)
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
21 ##
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
22 ## For vector arguments, std returns the standard deviation of the
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
23 ## values. For matrix arguments, std returns a row vector containing
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
24 ## the standard deviation for each column.
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
25 ##
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
26 ## See also: mean, median
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
27
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
28 ## Author: jwe
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
29
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
30 function retval = std (a)
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
31
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
32 if (nargin != 1)
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
33 usage ("std (a)");
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
34 endif
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
35
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
36 nr = rows (a);
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
37 nc = columns (a);
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
38 if (nc == 1 && nr == 1)
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
39 retval = 0;
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
40 elseif (nc == 1 || nr == 1)
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
41 n = length (a);
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
42 retval = sqrt (sumsq (a - mean (a)) / (n - 1));
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
43 elseif (nr > 1 && nc > 0)
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
44 retval = sqrt (sumsq (a - ones (nr, 1) * mean (a)) / (nr - 1));
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
45 else
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
46 error ("std: invalid matrix argument");
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
47 endif
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
48
781c930425fd [project @ 1998-10-29 05:23:08 by jwe]
jwe
parents:
diff changeset
49 endfunction