Some time ago I saw a thread in which was mentioned a root-finding algorithm that converges twice as fast as the Newton-Raphson method. Newton-Raphson converges to a zero at a quadratic rate, and a poster pointed out that another algorithm converges to a zero at a quartic rate. I have tried to find that thread, but cannot. Anybody here know what algorithm I am talking about? It is for computing the roots of a function and converges to a solution at twice the rate of Newton-Raphson?