# partial function

(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

## More information

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 Black.

Entry modified 11 February 2019.

HTML page formatted Tue Feb 12 10:57:43 2019.

Cite this as:

Paul E. Black, "partial function", in
*Dictionary of Algorithms and Data Structures* [online], Vreda Pieterse and Paul E. Black, eds. 11 February 2019. (accessed TODAY)
Available from: https://www.nist.gov/dads/HTML/partialfunct.html