中文说明： 使用起来非常方便，PLS部分最小二乘工具箱,用平面波展开法计算二维声子晶体带隙,包括脚本文件和函数文件形式，这是第二能量熵的matlab代码，利用最小二乘算法实现对三维平面的拟合。
English Description：
Very easy to use, PLS partial least squares Toolbox, using plane-wave expansion method for calculation of band gap of two-dimensional phononic crystals, including script files and function files, this is the second energy entropy of Matlab code, using least square fitting algorithm for three dimensional plane.