说明：  该程序是电磁场学习实验。用超松弛迭代法求解接地金属槽内的电位分布。 有个无限长直的金属槽，截面为正方形，两侧面及底板接地，上盖板与侧面绝缘，其上的电位为φ=100V，侧面电位φ=0V，试用有限差分法计算槽内的电位。内附编程思路等原理讲解
(The program is electromagnetic learning experiment. Solving the potential distribution of a grounded metal tank with super-relaxation method. There are an infinite long straight metal tank, square cross-section, the sides and bottom ground, on the side of the cover and insulation on the potential for φ = 100V, side potential φ = 0V, trial potential finite difference method tank . Included to explain the principles of programming ideas, etc.)