中文说明：%求解n乘n线性系统
English Description：
% To solve the n by n linear system % % E1: A(1,1) X(1) + A(1,2) X(2) +...+ A(1,n) X(n) = A(1,n+1) % E2: A(2,1) X(1) + A(2,2) X(2) +...+ A(2,n) X(n) = A(2,n+1) % : % . % EN: A(n,1) X(1) + A(n,2) X(2) +...+ A(n,n) X(n) = A(n,n+1) % % INPUT: number of unknowns and equations n; augmented % matrix A = (A(I,J)) where 1<=I<=n and 1<=J<=n+1. % % OUTPUT: solution x(1), x(2),...,x(n) or a message that the