4  1.d-6  1000  1.d0  ! n, tol, maxit , w
1.d0  2.d0  7.d0  4.d0  ! b(i)
5.d0 3.d0 -7.d0 8.d0 ! a(1,j)
0.d0 4.d0 0.d0 -5.d0  ! a(2,j)
-2.d0 5.d0 -8.d0 3.d0  ! a(3,j)
6.d0 -1.d0 0.d0 10.d0  ! a(4,j)