说明：  本代码是GAUSS-SEIDEL迭代法、选主元JORDAN消去法、简单GAUSS消去法、选主元GAUSS消去法的MATLAB程序，有详细注释，可直接调用
(This code is GAUSS-SEIDEL iteration, pivoting JORDAN elimination, simple GAUSS elimination, pivoting GAUSS elimination of the MATLAB program, with detailed notes, can be called directly)