In mathematics, a unary operation is an operation with only one operand, i.e. a single input. This is in contrast to binary operations, which use two operands. An example is any function f : A \rightarrow A, where A is a set. The function f is a unary operation on A. Common notations are prefix notation (e.g. ¬, −), postfix notation (e.g. factorial n! ), functional notation (e.g. sin x or sin(x) ), and superscripts (e.g. transpose AT ). Other notations exist as well, for example, in the case of the square root, a horizontal bar extending the square root sign over the argument can indicate the extent of the argument.

Examples

Absolute value

Obtaining the absolute value of a number is a unary operation. This function is defined as where |n| is the absolute value of n.

Negation

This is used to find the negative value of a single number. Here are some examples:

Factorial

For any positive integer n, the product of the integers less than or equal to n is a unary operation called factorial. In the context of complex numbers, the gamma function is an unary operation extension of factorial.

Trigonometry

In trigonometry, the trigonometric functions, such as \sin, \cos, and \tan, can be seen as unary operations. This is because it is possible to provide only one term as input for these functions and retrieve a result. By contrast, binary operations, such as addition, require two different terms to compute a result.

Examples from programming languages

Below is a table summarizing common unary operators along with their symbols, description, and examples:

JavaScript

In JavaScript, these operators are unary:

C family of languages

In the C family of languages, the following operators are unary:

Unix shell (Bash)

In the Unix shell (Bash/Bourne Shell), e.g., the following operators are unary:

PowerShell

In the PowerShell, the following operators are unary: