e(9) - 4
>>> a
array([-4, -3, -2, ...,  2,  3,  4])
>>> b = a.reshape((3, 3))
>>> b
array([[-4, -3, -2],
       [-1,  0,  1],
       [ 2,  3,  4]])

>>> LA.matrix_norm(b)
7.745966692414834
>>> LA.matrix_norm(b, ord='fro')
7.745966692414834
>>> LA.matrix_norm(b, ord=np.inf)
9.0
>>> LA.matrix_norm(b, ord=-np.inf)
2.0

>>> LA.matrix_norm(b, ord=1)
7.0
>>> LA.matrix_norm(b, ord=-1)
6.0
>>> LA.matrix_norm(b, ord=2)
7.3484692283495345
>>> LA.matrix_norm(b, ord=-2)
1.8570331885190563e-016 # may vary

ro