Notation (or Name) of the function which is 0 at x=0 and 1 otherwise Is there a traditional notation or name of this function:

$$
\epsilon (x)  = \begin{cases}
0 &amp; \textrm{ if }x = 0 \\
1 &amp; \textrm{ if }x \neq 0
\end{cases}
$$

I know one can use  Indicator function $1_{A}(x)$ for $A = \mathbb{R} - \{0\}$, but I still want to know if there is a traditional, simpler, notation for it.
The Kronecker delta function $\delta_{ij}$ is $1$ when $i=j$ and $0$ otherwise, so $\epsilon(x)=1-\delta_{0,x}$.
Here's one possible definition, though extremely dependent on how one defines the value $0^0$.

If you happen to subscribe to the belief that $0^0=0$ (disclaimer, I personally define $0^0=1$), then 
$$\epsilon(x)=x^0$$