本题采用的计算方法为：主要求解三对角阵方程组得解。采用的计算方法为“追赶法”。

算法思路为：求解方程Ly=d（追）——〉求解Ux=y（赶）

-that the use of the method of calculating : three pairs for the main diagonal matrix equations in the solution. Using the method of calculating "catch up law." Algorithm ideas : Solving equations Ly = d (recovery) -- "Solving Ux = y (rush)