### 2.37.20 Sort a list by decreasing order : `SortD`

`SortD` takes a list as argument.

`SortD` returns this list sorted by decreasing order.

Input :

`SortD([3,4,2])`

Output :

`[2,3,4]`

`SortD` may have a matrix as argument and in this case,
`SortD` modifies the order of columns by sorting the first matrix
row by decreasing order.

Input :

`SortD([[3,4,2],[6,4,5]])`

Output :

`[[4,3,2],[4,6,5]]`