用有限差分法来解偏微分方程，采用高斯——赛德尔迭代方法，并用前后两次迭代差的矩阵的无穷范数作为是否停止迭代的依据。-Using finite difference method to solve partial differential equations, using Gauss- Seidel iterative methods, and poor before and after the two iterations of the infinite matrix norm as the b