KroneckerDelta

KroneckerDelta[n1, n2, ...] gives the Kronecker delta δ_{n1 n2 ...}, equal to 1 if all the n_i are equal, and 0 otherwise.

Examples

Equal arguments:

KroneckerDelta[3, 3]
(* 1 *)

Unequal arguments:

KroneckerDelta[1, 2]
(* 0 *)

Multiple arguments:

KroneckerDelta[5, 5, 5]
(* 1 *)

Please visit the official Wolfram Language Reference for more details.