function yi=Newton(x, y, xi)
%newton基本插值公式
%(x,y)為插值點(diǎn)
%xi,yi為需要計(jì)算的點(diǎn)
n=length(x);
m=length(y);
Y=zeros(n);
Y(:,1)=y;
for k=1:n-1
   for i=1:n-k
       Y(i,k+1)=(Y(i+1,k)-Y(i,k))/(x(i+k)-x(i));
   end
end
yi=0;
for i=1:n
   z=1;
   for k=1:i-1
      z=z*(xi-x(k));
   end
   yi=yi+Y(1, i)*z;
end