说明：  一种变步长LMS的算法，描述了与基本LMS算法的比较，随着迭代次数的增加，变步长的LMS算法达到最优的迭代次数少
(A variable step size LMS algorithm, describes the basic LMS algorithm and compare that with the increase in the number of iterations, variable step size LMS algorithm to achieve the optimal number of iterations less)