Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / statistics-1.1.3 / trimmean.m

diff --git a/octave_packages/statistics-1.1.3/trimmean.m b/octave_packages/statistics-1.1.3/trimmean.m
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+## Copyright (C) 2001 Paul Kienzle <pkienzle@users.sf.net>
+##
+## 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/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {@var{a} =} trimmean (@var{x}, @var{p})
+##
+## Compute the trimmed mean.
+##
+## The trimmed mean of @var{x} is defined as the mean of @var{x} excluding the
+## highest and lowest @var{p} percent of the data.
+##
+## For example
+##
+## @example
+## mean ([-inf, 1:9, inf])
+## @end example
+##
+## is NaN, while
+##
+## @example
+## trimmean ([-inf, 1:9, inf], 10)
+## @end example
+##
+## excludes the infinite values, which make the result 5.
+##
+## @seealso{mean}
+## @end deftypefn
+
+function a = trimmean(x, p, varargin)
+  if (nargin != 2 && nargin != 3)
+    print_usage;
+  endif
+  y = sort(x, varargin{:});
+  sz = size(x);
+  if nargin < 3
+    dim = min(find(sz>1));
+    if isempty(dim), dim=1; endif;
+  else
+    dim = varargin{1};
+  endif
+  idx = cell (0);
+  for i=1:length(sz), idx{i} = 1:sz(i); end;
+  trim = round(sz(dim)*p*0.01);
+  idx{dim} = 1+trim : sz(dim)-trim;
+  a = mean (y (idx{:}), varargin{:});
+endfunction