How to use epsilon(ϵ,ε) and backepsilon(϶) symbol in LaTeX?

The Greek letter Epsilon is a popular symbol of Mathematica. You need to use the \epsilon command to write this symbol in latex. Below is how to use it in latex.

\documentclass{article}
\begin{document}
   \[ \lim_{\epsilon\rightarrow 0^+} \frac{1}{\epsilon^2 N(\epsilon)} \]
   \[ p < \epsilon \]
   \[ \lim_{\epsilon\rightarrow 0} \frac{1}{\pi x}\sin\left(\frac{x}{\epsilon}\right) \]
\end{document}

Output :

Varepsilon symbol in LaTeX

LaTeX provides a default command to print the varepsilon symbol in a LaTeX document, which is \varepsilon. And if you want to print this symbol in upper case then use \mathcal{E} command. You don’t need any package for this.

\documentclass{article}
\begin{document}
  \[ \verb|\epsilon|\longrightarrow \epsilon \]
  \[ \verb|\varepsilon|\longrightarrow \varepsilon \]
  \[ \verb|\mathcal{E}|\longrightarrow \mathcal{E} \]
\end{document}

Output :

Backepsilon symbol in LaTeX

You will need the amssymb package to print backepsilon symbols to a LaTeX document. This package provides a command called \backepsilon, which allows you to print this symbol in a document.

\documentclass{article}
\usepackage{amssymb}
\begin{document}
  \[ \verb|\epsilon|\longrightarrow \epsilon \]
  \[ \verb|\backepsilon|\longrightarrow \backepsilon \]
\end{document}

Output :