Norms of a vector : maxnorm l1norm l2norm norm

### 2.38.1 Norms of a vector : `maxnorm l1norm l2norm norm`

The instructions to compute the different norm of a vector are :

- `maxnorm` returns the l∞ norm of a vector, defined as the maximum of the absolute values of its coordinates.
  Input :
  `maxnorm([3,-4,2])`
  Output :
  `4`
  Indeed : `x=3, y=-4, z=2` and `4=max(|x|,|y|,|z|)`.
- `l1norm` returns the `l``1` norm of a vector defined as the sum of the absolute values of its coordinates.
  Input :
  `l1norm([3,-4,2])`
  Output :
  `9`
  Indeed : `x=3, y=-4, z=2` and `9=|x|+|y|+|z|`.
- `norm` or `l2norm` returns the l2 norm of a vector defined as the square root of the sum of the squares of its coordinates.
  Input :
  `norm([3,-4,2])`
  Output :
  `sqrt(29)`
  Indeed : `x=3, y=-4, z=2` and 29=|x|2+|y|2+|z|2.