function box=difftable(x,y)
%This routine calculates the table of divided differences
%for the data  (x(i),y(i)).
s=size(y);
n=s(1);
box=zeros(n,n);
%Initialize the first column of the difference table = y.
for ii=1:n
    box(ii,1)=y(ii);
end
%Compute the table of divided differences.
for k=2:n
    for ii=1:n-k+1
        box(ii,k)=(box(ii+1,k-1)-box(ii,k-1))/(x(ii+k-1)-x(ii));
    end
end