How do I use \renewcommand to get BACK my greek letters? <p>I'm a LaTeX newbie, but I've been doing my homework, and now I have a question that I can't seem to find the answer to. I create the definition of an equation, let's just say it's this one:</p> <pre><code>The potential is characterized by a length $\sigma$ and an energy $\epsilon$. </code></pre> <p>In reality, this equation is more complex, which is why I wanted to try a shortcut. If my equation were this simplistic, I wouldn't try my substitution technique. I use the \renewcommand to save me some time:<BR></p> <pre><code>\renewcommand{\sigma}{1} </code></pre> <p>And this works fabulously and will replace all instances of sigma with 1. Unfortunately though, since \sigma has a global scope, I need to reset it. I tried a couple different ways:<BR> Attempt 1: -deadlock due to circular reference?</p> <pre><code>\newcommand{\holdsigma}{\sigma} \renewcommand{\sigma}{1} The potential is characterized by a length $\sigma$ and an energy $\epsilon$. \renewcommand{\sigma}{\holdsigma} </code></pre> <p>I would think to reset the command, it should look something like this:</p> <pre><code>\renewcommand{\sigma}{\greek{\sigma}} </code></pre> <p>but that obviously hasn't worked out for me.<BR><BR> Any idea about how the greek letters are originally defined in the language?</p>