(50G) Inverse Permutation

[Didier Lachieze]

Does it return the same error message for {1 3 3 4 5}?

Here is the updated version with error handling:

Code:

EXPORT InvPerm(list)
BEGIN
  LOCAL p;
  MAKELIST(IFTE(p:=POS(list,X),p,ASC(0)),X,1,SIZE(list));
END;