TITLE: Notation For Delta Distribution
QUESTION [1 upvotes]: 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?

REPLY [2 votes]: The first describes a delta function acting at the origin.

The second describes a delta function acting along the line $x=y$:
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