• Orderless is an attribute that can be assigned to a symbol f to indicate that the elements in expressions of the form f[, , ... ] should automatically be sorted into canonical order. This property is accounted for in pattern matching.
• The Orderless attribute for a function corresponds to the mathematical property of commutativity.
• Functions with the Orderless
attribute use canonical order as described in the notes for Sort
• For an object that represents a matrix or a tensor, the Orderless attribute represents symmetry among indices.
• Functions like Plus
• In matching patterns with Orderless functions, all possible orders of arguments are tried.
• The Orderless attribute must be assigned before defining any values for an Orderless function.
• New in Version 1.