# Kronecker delta

In mathematics, the **Kronecker delta** is a function of two variables, which is 1 if they are equal, and 0 otherwise. It is written as the symbol δ_{ij}, and treated as a notational shorthand rather than a function.

It is used in many areas of mathematics. For example, in linear algebra, the identity matrix can be written as:

- (δ
_{ij})