(definition)

**Definition:**
A *function* which is not defined for some inputs of the right type, that is, for some of a *domain*. For instance, division is a partial function since division by 0 is undefined (on the Reals).

**See also**
*total function*, *partial recursive function*.

*Note:
This definition says a function is either partial or total, but not both. Some authors consider that all functions are partial, but some are total, too.*

Author: PEB

Wikipedia entry for partial function.

Go to the Dictionary of Algorithms and Data Structures home page.

If you have suggestions, corrections, or comments, please get in touch with Paul E. Black.

Entry modified 13 September 2007.

HTML page formatted Tue Dec 6 16:16:32 2011.

Cite this as:

Paul E. Black, "partial function", in
*Dictionary of Algorithms and Data
Structures* [online], Paul E. Black, ed.,
U.S. National Institute of
Standards and Technology. 13 September 2007. (accessed TODAY)
Available from: http://www.nist.gov/dads/HTML/partialfunct.html