二维声子晶体FDTD方法计算禁带宽度的例子,包括压缩比、运行时间和计算复原图像的峰值信噪比,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, Including compression ratio, image restoration computing uptime and peak signal to noise ratio, This func