function out=newton(f, df, x1, tol, n)
x(1)=x1;
i=2;
while i<=n
x(i)=x(i-1)-f(x(i-1))/df(x(i-1));
if f(x(i))==0 || abs(x(i)-x(i-1))<tol
break;
end
i = i + 1;
end
if i>n
k=1:n;
else
k=1:i;
end
out=[k', x(k)', f(x(k))'];