Encyclopedia > Function domain

  Article Content

Function domain

In mathematics, given a function fA → B, the set A is called the domain, or domain of definition of f.

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

has no valid value for f(0). It is thus not a function on the set R of real numbers; R can't be its domain. It is usually either defined as a function on R \ {0}, or the "gap" is plugged by specifically defining f(0); for example:

f: x → 1/x , x ≠ 0
f: 0 → 0

The domain of given function can be restricted to a subset. Suppose that gA → B, and S ⊆ A. Then the restriction of g to S is written:

g|S: SB


See also: Function codomain



All Wikipedia text is available under the terms of the GNU Free Documentation License

 
  Search Encyclopedia

Search over one million articles, find something about almost anything!
 
 
  
  Featured Article
Canadian Charter of Rights and Freedoms

... rights legal rights: the right to be presumed innocent until proven guilty, the right to retain a lawyer and to be informed of that right, and the right to a ...

 
 
 
This page was created in 31.8 ms