function [xn,err,n] =newton(x0, tol, maxiter) xn(1) = x0; n=1; err(1)=tol+1; while (err(n)>tol) & (n<=maxiter) n=n+1; xn(n)=xn(n-1)-f(xn(n-1))/flinha(xn(n-1)); err(n)=abs((xn(n)-xn(n-1))/xn(n)); end end function y=f(x) y=x*x*x-2*x*x-5; end function y=flinha(x) y=3*x*x-4*x; end return