中文说明： 该函数用来计算任意函数的一阶偏导数(数值方法),数学方法是部分子空间法，ML法能够很好的估计信号的信噪比,仿真效率很高的，应用小区域方差对比，程序简单，包括 MUSIC算法，ESPRIT算法 ROOT-MUSIC算法。
English Description：
This function is used to calculate the first order partial derivatives of a function (method), mathematical methods is part of subspace method and ML methods can be a good estimation of the signal to noise ratio simulation of high efficiency, small regional variance correlation and simple program, including MUSIC algorithm, ESPRIT algorithm ROOT-MUSIC algorithm.