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median.m
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1999-04-29
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## Copyright (C) 1996, 1997 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: median (a)
##
## For vector arguments, return the median of the values.
##
## For matrix arguments, return a row vector containing the median for
## each column.
##
## See also: std, mean
## Author: jwe
function retval = median (a)
if (nargin != 1)
usage ("median (a)");
endif
[nr, nc] = size (a);
s = sort (a);
if (nr == 1 && nc > 0)
if (rem (nc, 2) == 0)
i = nc/2;
retval = (s (i) + s (i+1)) / 2;
else
i = ceil (nc/2);
retval = s (i);
endif
elseif (nr > 0 && nc > 0)
if (rem (nr, 2) == 0)
i = nr/2;
retval = (s (i,:) + s (i+1,:)) / 2;
else
i = ceil (nr/2);
retval = s (i,:);
endif
else
error ("median: invalid matrix argument");
endif
endfunction