中文说明：针对三维声子晶体结构，采用有限元法编写MATLAB程序，就算得到结构的带隙特性！如有不足之处请指正，欢迎大家多多交流！！！
English Description：
For the three-dimensional phononic crystal structure, using the finite element method to write the matlab program, even get the band gap characteristics of the structure! If there are any shortcomings, please correct, welcome to exchange more!!!