statistics.m

GNU Octave is a high-level language, primarily intended for numerical computations. It provides a c

## Copyright (C) 1995, 1996, 1997  Kurt Hornik
## 
## 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 2, 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 file.  If not, write to the Free Software Foundation,
## 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

## usage:  S = statistics (X)
##
## If X is a matrix, return a matrix S with the min, first quartile,
## median, third quartile, max, mean, std, skewness and kurtosis of the
## columns of X as its rows.
##
## If X is a vector, treat it as a column vector.
  
## Author:  KH <[e-mail]>
## Description:  Compute basic statistics

function S = statistics (X)
  
  if (nargin != 1)
    usage ("S = statistics (X)");
  endif

  if (prod (size (X)) > 1)
    if (is_vector (X))
      X = reshape (X, length (X), 1);
    endif
    for k=1:columns(X)
      S(:,k) = [(min (X(:,k)));
		(empirical_inv ([0.25;0.5;0.75], X(:,k)));
	 	(max (X(:,k)));
		(mean (X(:,k)));
		(std (X(:,k)));
		(skewness (X(:,k)));
		(kurtosis (X(:,k)))];
    endfor 
  else
    error ("statistics:  invalid argument");
  endif
  
endfunction