A5 matrix for testing A=LU-decomposition
5
  10.0   1.0   2.0   3.0   4.0
   1.0   9.0  -1.0   2.0  -3.0
   2.0  -1.0   7.0   3.0  -5.0
   3.0   2.0   3.0  12.0  -1.0
   4.0  -3.0  -5.0  -1.0  15.0


Output matrices L and U are stored in the input matrix A 
   10.0000    1.0000    2.0000    3.0000    4.0000
    0.1000    8.9000   -1.2000    1.7000   -3.4000
    0.2000   -0.1348    6.4382    2.6292   -6.2584
    0.3000    0.1910    0.4084    9.7016    1.0052
    0.4000   -0.3820   -0.9721    0.1036    5.9133

Matrices L, U for A=LU in [L U P=I]=lu(A)