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 iteration is superior to that of the last iteration)