A Dirac delta function or simply delta function is a generalized function on the real number line denoted by δ that is zero everywhere except at zero, with an integral of one over the entire real line.
Delta function may also refer to:
- Kronecker delta, a function of two variables which is one for equal arguments and zero otherwise, and which forms the identity element of an incidence algebra
- Modular discriminant (Δ), a complex function in Weierstrass's elliptic functions