|
7017
|
1 ## Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2002, 2003, 2005, |
|
|
2 ## 2006, 2007 Kurt Hornik |
|
3426
|
3 ## |
|
3922
|
4 ## This file is part of Octave. |
|
|
5 ## |
|
|
6 ## Octave is free software; you can redistribute it and/or modify it |
|
|
7 ## under the terms of the GNU General Public License as published by |
|
7016
|
8 ## the Free Software Foundation; either version 3 of the License, or (at |
|
|
9 ## your option) any later version. |
|
3426
|
10 ## |
|
3922
|
11 ## Octave is distributed in the hope that it will be useful, but |
|
3200
|
12 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
|
|
13 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
|
3426
|
14 ## General Public License for more details. |
|
|
15 ## |
|
3200
|
16 ## You should have received a copy of the GNU General Public License |
|
7016
|
17 ## along with Octave; see the file COPYING. If not, see |
|
|
18 ## <http://www.gnu.org/licenses/>. |
|
3200
|
19 |
|
3367
|
20 ## -*- texinfo -*- |
|
4022
|
21 ## @deftypefn {Function File} {} mean (@var{x}, @var{dim}, @var{opt}) |
|
3367
|
22 ## If @var{x} is a vector, compute the mean of the elements of @var{x} |
|
|
23 ## @iftex |
|
|
24 ## @tex |
|
|
25 ## $$ {\rm mean}(x) = \bar{x} = {1\over N} \sum_{i=1}^N x_i $$ |
|
|
26 ## @end tex |
|
|
27 ## @end iftex |
|
|
28 ## @ifinfo |
|
3426
|
29 ## |
|
3367
|
30 ## @example |
|
|
31 ## mean (x) = SUM_i x(i) / N |
|
|
32 ## @end example |
|
|
33 ## @end ifinfo |
|
|
34 ## If @var{x} is a matrix, compute the mean for each column and return them |
|
|
35 ## in a row vector. |
|
3200
|
36 ## |
|
3367
|
37 ## With the optional argument @var{opt}, the kind of mean computed can be |
|
|
38 ## selected. The following options are recognized: |
|
|
39 ## |
|
|
40 ## @table @code |
|
|
41 ## @item "a" |
|
|
42 ## Compute the (ordinary) arithmetic mean. This is the default. |
|
|
43 ## |
|
|
44 ## @item "g" |
|
7001
|
45 ## Compute the geometric mean. |
|
3367
|
46 ## |
|
|
47 ## @item "h" |
|
|
48 ## Compute the harmonic mean. |
|
|
49 ## @end table |
|
4022
|
50 ## |
|
|
51 ## If the optional argument @var{dim} is supplied, work along dimension |
|
|
52 ## @var{dim}. |
|
|
53 ## |
|
|
54 ## Both @var{dim} and @var{opt} are optional. If both are supplied, |
|
|
55 ## either may appear first. |
|
3367
|
56 ## @end deftypefn |
|
3426
|
57 |
|
5428
|
58 ## Author: KH <Kurt.Hornik@wu-wien.ac.at> |
|
3456
|
59 ## Description: Compute arithmetic, geometric, and harmonic mean |
|
3200
|
60 |
|
4022
|
61 function y = mean (x, opt1, opt2) |
|
|
62 |
|
|
63 need_dim = 0; |
|
3200
|
64 |
|
4022
|
65 if (nargin == 1) |
|
|
66 opt = "a"; |
|
|
67 need_dim = 1; |
|
|
68 elseif (nargin == 2) |
|
5443
|
69 if (ischar (opt1)) |
|
4022
|
70 opt = opt1; |
|
|
71 need_dim = 1; |
|
|
72 else |
|
4525
|
73 dim = opt1; |
|
4022
|
74 opt = "a"; |
|
|
75 endif |
|
|
76 elseif (nargin == 3) |
|
5443
|
77 if (ischar (opt1)) |
|
4022
|
78 opt = opt1; |
|
|
79 dim = opt2; |
|
5443
|
80 elseif (ischar (opt2)) |
|
4022
|
81 opt = opt2; |
|
|
82 dim = opt1; |
|
|
83 else |
|
6046
|
84 error ("mean: expecting opt to be a string"); |
|
4022
|
85 endif |
|
|
86 else |
|
6046
|
87 print_usage (); |
|
3200
|
88 endif |
|
3426
|
89 |
|
4022
|
90 if (need_dim) |
|
|
91 t = find (size (x) != 1); |
|
|
92 if (isempty (t)) |
|
|
93 dim = 1; |
|
|
94 else |
|
|
95 dim = t(1); |
|
|
96 endif |
|
3200
|
97 endif |
|
|
98 |
|
5243
|
99 if (dim > ndims (x)) |
|
|
100 n = 1; |
|
|
101 else |
|
|
102 sz = size (x); |
|
|
103 n = sz (dim); |
|
|
104 endif |
|
3426
|
105 |
|
3200
|
106 if (strcmp (opt, "a")) |
|
4022
|
107 y = sum (x, dim) / n; |
|
3200
|
108 elseif (strcmp (opt, "g")) |
|
4022
|
109 x(x <= 0) = NaN; |
|
|
110 y = exp (sum (log (x), dim) / n); |
|
3200
|
111 elseif (strcmp (opt, "h")) |
|
4022
|
112 x(x == 0) = NaN; |
|
|
113 y = n ./ sum (1 ./ x, dim); |
|
3200
|
114 else |
|
3456
|
115 error ("mean: option `%s' not recognized", opt); |
|
3200
|
116 endif |
|
3426
|
117 |
|
3200
|
118 endfunction |
