%  define the function f
%  define initial iterate x_1 and x_2 as components of a VECTOR 
%  in advance

R = zeros(10,5);
R(1,1) =1;  R(1,2) = x(1); R(1,3) = f(x(1));
for k=2:10
R(k,1) = k;
R(k,2) = x(2);  
R(k,3) = f(x(2));  R(k,4) = (R(k,3)-R(k-1,3))/(x(2)-x(1));
R(k,5) = -R(k,3)/R(k,4);
x(1) = x(2); x(2) = x(1) + R(k,5);
end