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