Notation For Delta Distribution I've encountered two different notations for the delta distribution:
$$\delta(x,y)$$
and
$$\delta(x-y)$$
What is the difference between these two notations. Do they depend on context or should I prefer one over the other?

The first notation is more convenient when working in high dimensions, since it naturally generalizes to $n$ dimensions:  e.g., $\delta (x,y,z,w, ...)$.  You can do this with the second notation $\delta(x) \delta(y), ...$  
Certain software (e.g., Mathematica) supports both usages. 
