（1） 编制解n阶线性代数方程组AX=b列主元三角分解法的通用程序. （2） 用所编的程序解线性方程组.给出解向量,保留5位有效数. -(1) the preparation of solution of n-order linear algebraic equations AX = b out PCA generic triangular decomposition process. (2) the procedures used by the series solution of l