最大似然（ML）准则和最大后验概率（MAP）准则，随机调制信号下的模拟ppm，该函数用来计算任意函数的一阶偏导数(数值方法)。- Maximum Likelihood (ML) criteria and maximum a posteriori (MAP) criterion, Random ppm modulated analog signal under This function is used to calculate the arbitrary function of the first order partial derivative (numerical methods).