DiscreteDelta

DiscreteDelta[n1, n2, ...] gives the discrete delta function δ(n1, n2, ...), equal to 1 if all ni are zero, and 0 otherwise.

Examples

Single argument:

DiscreteDelta[0]
(* 1 *)

DiscreteDelta[5]
(* 0 *)

Multiple arguments:

DiscreteDelta[0, 0, 0]
(* 1 *)

Please visit the official Wolfram Language Reference for more details.