开始选择一个与之作为初始估计值，按照某种规则更新估计值，直至满足给定条件，此种方法迭代迅速收敛，每次迭代结果优于上次迭代(By choosing one as the initial estimate and updating the estimate according to some rule until the given condition is satisfied, the method converges quickly, and the result of each iterati