三相光伏逆变并网的仿真，该函数用来计算任意函数的一阶偏导数(数值方法),利用贝叶斯原理估计混合logit模型的参数。- Three-phase photovoltaic inverter and network simulation, This function is used to calculate the arbitrary function of the first order partial derivative (numerical methods), Bayesian parameter estimation principle mixed logit model.