Quadratic convergence bound for Newton's method (source code)

= Quadratic convergence bound for Newton's method

If $\nabla^2f\succeq mI$ and the Hessian is $M$-Lipschitz near a minimizer $x^*$, then
$$
\|x_{k+1}-x^*\|\leq\frac{M}{2m}\|x_k-x^*\|^2.
$$
Thus a sufficiently close initial point has an error exponent that doubles at each iteration.