二维声子晶体FDTD方法计算禁带宽度的例子,利用贝叶斯原理估计混合logit模型的参数，该函数用来计算任意函数的一阶偏导数(数值方法)。- Dimensional phononic crystals FDTD method calculation examples band gap, Bayesian parameter estimation principle mixed logit model, This function is used to calculate the arbitrary function of the first order partial derivative (numerical methods).