function yi=newton(x,y,w)

n=length(x);m=length(y);

if n~=m

    'error'

    return;

end

Y=zeros(n);Y(:,1)=y';

for i=2:n

    for k=2:i

        Y(i,k)=(Y(i,k-1)-Y(i-1,k-1))/(x(i)-x(i-k+1));

    end

end

 

    yi=0;

    for i=1:n

z=1;

        for k=1:i-1

 

            z=z.*(w-x(k));

 

        end

        yi=yi+Y(i,i)*z;

    end