clear all;
x0=[1 2 3 4 5 6];
y0=[1 4 9 16 25 36];
x=[1.5 2.5 3.5 4.5 5.5];
EPS=0.01;
k=1;
y=lagrange(x0,y0,x);
for i=1:5
y1=(y(i)-x(i)*x(i))*(y(i)-x(i)*x(i));
if y1<=EPS
    z=y;
else
    k=k+1;
    y=lagrange(x0,y0,x);
end
plot(y0,'r');
hold on;
plot(y,'y');
end