function P=DivdiffDeriv(X,Y,x)
coeff=Divdiffcoeff(X,Y);
P=0;
for j=1:10
    S=0;
    for k=1:j-1
        T=1;
        for i=1:j-1
            if(i~=k)
                T=T*(x-X(i));
            end
        end
        S=S+T;
    end
    P=P+coeff(j)*S;
end