partialfunction
nounUK /ˈpɑːʃəl ˈfʌŋkʃən/
US /ˈpɑːrʃəl ˈfʌŋkʃən/
A partial function is a rule that gives an answer for only some of the things you put in.
Dividing by a number is a partial function because it has no answer when you divide by zero.
RELATED WORDS
OTHER MEANINGS
2. In computer programming, a function that is not defined for every possible input.
The lookup function is partial because it fails when the key is missing.
3. In mathematics, a relation that pairs each input with at most one output, but not necessarily every input.
The square root is a partial function on the real numbers because negative numbers have no real root.
4. A function whose domain is a proper subset of a larger set under discussion.
On the integers, division is only a partial function.