(definition)

**Definition:**
A computation which takes some inputs and yields an output. Any particular input may yield different outputs at different times. Formally, a mapping from each element in the *domain* to one or more elements in the *range*.

**Specialization** (... is a kind of me.)

*function*, *binary relation*.

*Note:
Cosine is a function, since every angle has a specific cosine. Its inverse cos ^{-1}(x) is a relation, since a cosine value maps to many (for this relation, infinitely many) angles.*

Author: PEB

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Entry modified 18 December 2003.

HTML page formatted Fri Feb 23 10:06:08 2018.

Cite this as:

Paul E. Black, "relation", in
*Dictionary of Algorithms and Data Structures* [online], Vreda Pieterse and Paul E. Black, eds. 18 December 2003. (accessed TODAY)
Available from: https://www.nist.gov/dads/HTML/relation.html