说明：  使用有限元方法求解漫射方程,其中所需要的三维有限元网格来自netgen软件。压缩包中包含了网格数据文件和源代码。代码运行之前首先要注意修改源代码中的网格文件的存放路径。
(solve the diffusion equation with finite method,the mesh which is used in it is generated by netgen。A matlab source code and a mesh file is include in it. The mesh file path should be set before running the sourcecode.)