In mathematics, a function domain is a description of the possible input values to a function.
Given a function f: A → B, the set A is called the domain, or domain of definition of f.
The set of all values in the codomain that f maps to is called the range of f, or f(A).
A well-defined function must map every element of the domain to an element of its codomain. So, for example, the function:
- f: x → 1/x
- f: x → 1/x , x ≠ 0
- f: 0 → 0
- g|_{S}: S → B
See also: Function codomain, Function range, Injective, Surjective, Bijective