This is documentation for Mathematica 4, which was
based on an earlier version of the Wolfram Language.

Ordering

Ordering[list] gives the positions in list at which each element of Sort[list] appears.

Ordering[list, n] gives the positions in list at which the first n elements of Sort[list] appear.

Ordering[list, -n] gives the positions of the last n elements of Sort[list].

Ordering[list, n, p] uses Sort[list, p].

Example: Ordering[c, a, b] .

In a numerical list Ordering[list, n] gives the positions of the n smallest elements. Ordering[list, -n] gives the positions of the n largest elements.

If there are several smallest elements in list, Ordering[list, 1] will give only the position of the one that appears first.

list[[Ordering[list]]] is the same as Sort[list].

Ordering[list, seq] is equivalent to Take[Ordering[list], seq].

Ordering[list, All, p] gives the position at which all elements of list appear in Sort[list, p].

Ordering can be used on expressions with any head, not only List.

See The Mathematica Book: Section 1.8.13.

See also: Max, Min, Position, OrderedQ.