浙大PTA练习系统NA1004 比较雅各比迭代和高斯塞德尔迭代-Use Jacobi and Gauss-Seidel methods to solve a given n×n linear system A

x

⃗

=

b

⃗

　with an initial approximation

x

⃗



(0)

.

Note: When checking each a

ii

, first scan downward for the entry with maximum absolute value (a

ii

　included). If that entry is non-zero, swap it to the diagonal. Otherwise if that entry is zero, scan upward for the entry with maximum absolute value. If that entry is non-zero, then add that row to the i-th row.