说明：  poisson问题有限元求解通用程序(线性元). 压缩包内exp.m包含了一个实际问题,matlab下直接运行即可,如效率不高,可适当修改网格参数h.
(poisson problem of the finite element procedure for solving general (linear million). exp.m compressed package contains a real problem, matlab can be directly run, such as the efficiency is not high, may be appropriate to amend the grid parameter h.)