算法：利用doolittle分解进行算法，对方程组进行求解。 程序可以直接运行。用户可以对该程序进行小的改动就可以编写成对任意阶数的方程组求解函数。-Algorithms: the use of doolittle decomposition algorithm, the equations to solve it. Programs can be run directly. Users can carry out minor changes to the program you can w