exercise1:

x1 =  [4. 6. 7.]
x2 =  [7. 5. 6.]
x3 =  [1. 5. 4.]

L1  L2  Linf norms

17.0 10.04987562112089 7.0
18.0 10.488088481701515 7.0
10.0 6.48074069840786 5.0