function P = LagrangeDeriv(X,Y,x)

P=0;
for k=1:10
    S=0;
    for i=1:10
        if(i~=k)
            T=1/(X(k)-X(i));
            for j=1:10
                if(j~=i & j~=k)
                    T=T*(x-X(j))/(X(k)-X(j));
                end
            end
            S=S+T;
        end
 
    end
    P=P+Y(k)*S;
end