function D=difdiv(x,f)
n=length(x);
D=zeros(n,n);
D(:,1)=f';

for j=2:n
   for i=j:n
      D(i,j)=(D(i,j-1)-D(i-1,j-1))/(x(i)-x(i-j+1));
   end
   
end
D