A unary function is a function that takes one argument. A unary operator belongs to a subset of unary functions, in that its range coincides with its domain. In contrast, a unary function's domain may or may not coincide with its range. Examples The successor function, denoted , is a unary operator. Its domain and codomain are the natural numbers, its definition is as follows: In many programming languages such as C, executing this operation is denoted by postfixing to the operand, i.e. the use of is equivalent to executing the assignment . Many of the elementary functions are unary functions, including the trigonometric functions, logarithm with a specified base, exponentiation to a particular power or base, and hyperbolic functions. See also Arity Binary function Binary operator List of mathematical functions Ternary operation Unary operation References Foundations of Genetic Programming Functions and mappings Types of functions