Unary operation

In mathematics, a unary operation is an operation with only one operand, i.e. an operation with a single input, or in other words, a function of one variable (for the terminology see also operators versus functions).

Common notations are prefix notation (+, −, not), postfix notation (factorial: n!), and functional notation (sin x or sin (x)). 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, so that parentheses can be dispensed with.

Examples of Unary Operations

• the absolute value operation is a unary operation on the real numbers
• the opposite operation (−x) on the real numbers
• the power operations (squaring, cubing, etc) on the real numbers
• the factorial operation on the real numbers
• the trigonometric functions (sin x, cos x, tan x, cot x, csc x, sec x) on the real numbers
• the natural logarithm (ln x) on the real numbers
• the logarithm of base 10 (log x) on the real numbers
• logical negation on truth values
• A unary operation on a given set S is a function S → S, also called an endomorphism of S.

Computer Programming

Unary operators (called "monadic" in APL) are also used in programming languages. For example, in the C family of languages, the following operators are unary:

• Increment: ++x, x++
• Decrement: −−x, x−−
• Address: &x
• Indirection: *x
• Positive: +x
• Negative: −x
• One's complement: ~x
• Logical negation: !x
• Sizeof: sizeof x
• Sizeof: sizeof(type-name)
• Cast: (type-name) cast-expression

Usage of Incremental and Decremental Operators

In most programming languages, incremental and decremental operators can be preffixed and suffixed to the variable. The preffix and suffix can be useful when manipulating variables. A suffixed operation increments the value after it has been called.

Example 1

int i = 0;
printf (" %i \n %i ", i++ , i++ );
Output:
0
1

Whereas a prefixed operation will increment the value before it has been called.

Example 2

int i = 0;
printf (" %i \n %i ", ++i, ++i);
Output
1
2
The usage of incremental and decremental operators is usually found in For loops

See also

• Binary operation
• Ternary operation
• Arity
• Operand
• Operator
• Operator (programming)cs:Unární operace

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