function px = newtonpoly(knot,cf,x)
% Calculates the values px of Newton's interpolation polynomial at x
% knot : nodes of the polynomial
% cf : vector containing the values of the function at the nodes
% x : vector

[c,w] = divdiff(knot,cf);
lw=length(w);
px = w(1);
y = 1;
for k = 2:lw
    y = y.*(x-knot(k-1));
    px = px+w(k)*y;
end