f ( x ) = { e − 1 / x 2 if x ≠ 0 0 if x = 0 {\displaystyle f(x)={\begin{cases}e^{-1/x^{2}}&{\text{if }}x\neq 0\\[3mu]0&{\text{if }}x=0\end{cases}}}
![{\displaystyle f(x)={\begin{cases}e^{-1/x^{2}}&{\text{if }}x\neq 0\\[3mu]0&{\text{if }}x=0\end{cases}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/ae050e61cde6a0fdeda1f237f75846465579462d)
