Unary Operation

In mathematics, a unary operation is an operation with only one operand, i.e. a single input. Specifically, it is a function

where A is a set. In this case f is called an unary operation on A.

Common notations are prefix notation (e.g. +, −, not), postfix notation (e.g. factorial: n!), functional notation (e.g. sin x or sin (x)), and superscripts (e.g. transpose AT). Other notation exists as well, for example in the case of the square root a horizontal bar over the argument extending the square root sign can indicate the extent of the argument.