lagrange.m

追赶法

function y=lagrange(x0,y0,x);
n=length(x0);m=length(x);
for i=1:m
  z=x(i);
  s=0.0;
  for k=1:n
      p=1.0;
      for j=1:n
          if j~=k
            p=p*(z-x0(j))/(x0(k)-x0(j));
          end
      end
      s=p*y0(k)+s;
  end
    y(i)=s;
end