% 
% Written by:
% -- 
% John L. Weatherwax                2007-07-01
% 
% email: wax@alum.mit.edu
% 
% Please send comments and especially bug reports to the
% above email address.
% 
%-----

clc; 
format rat; 

tab = [ 3, 2, 1, 0, 0, 0, 4; 3, 1, 0, 1, 0, 0, 3; 2, 0, 0, 0, 1, 0, 3; -2, -1, 0, 0, 0, 1, 0 ]
	 
tab(2,:) = tab(2,:)/3;
tab(1,:) = -3 * tab(2,:) + tab(1,:);
tab(3,:) = -2 * tab(2,:) + tab(3,:); 
tab(4,:) = +2 * tab(2,:) + tab(4,:); 
tab

tab(2,:) = (-1/3) * tab(1,:) + tab(2,:);
tab(3,:) = (2/3) * tab(1,:) + tab(3,:);
tab(4,:) = (1/3) * tab(1,:) + tab(4,:);
tab