Indicator Function - Definition

Definition

The indicator function of a subset of a set is a function

defined as

\mathbf{1}_A(x) =
\begin{cases}
1 &\text{if } x \in A, \\
0 &\text{if } x \notin A.
\end{cases}

The Iverson bracket allows the equivalent notation, to be used instead of

The function is sometimes denoted or or even just . (The Greek letter χ appears because it is the initial letter of the Greek word characteristic.)

Read more about this topic:  Indicator Function

Famous quotes containing the word definition:

    The very definition of the real becomes: that of which it is possible to give an equivalent reproduction.... The real is not only what can be reproduced, but that which is always already reproduced. The hyperreal.
    Jean Baudrillard (b. 1929)

    The definition of good prose is proper words in their proper places; of good verse, the most proper words in their proper places. The propriety is in either case relative. The words in prose ought to express the intended meaning, and no more; if they attract attention to themselves, it is, in general, a fault.
    Samuel Taylor Coleridge (1772–1834)

    I’m beginning to think that the proper definition of “Man” is “an animal that writes letters.”
    Lewis Carroll [Charles Lutwidge Dodgson] (1832–1898)