# Undefined control sequence \eq

I am just starting using LaTeX and there's a problem I cannot solve. See, I want to make a plan so I use this code :

\documentclass[a4paper,12pt,landscape]{slides}

\usepackage[latin1]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[frenchb]{babel}
\usepackage{lmodern}
\usepackage{geometry}
\geometry{hmargin=1.5cm,vmargin=1.5cm}
\usepackage{calc}
\usepackage{enumitem}

\begin{document}

\title{Dynamique des fonctions et le probl$\grave{e}$me du chaos}

\textit{Probl$\acute{e}$matique : }
Pouvons-nous trouver une mani$\grave{e}$re de corriger la composante chaotique d'un syst$\grave{e}$me ?

\begin{enumerate}
\item \emph{Introduction au chaos : la famille des fonctions quadratiques : $Q_{\mu}(x)\eq \mu.x.(1-x)$}

\begin{itemize}%[label = \Alph*]
\item[A] D$\acute{e}$but d'analyse : points fixes attracteurs
\item[B] Apparition du chaos, d$\acute{e}$finitions
\end{itemize}

\item \emph{Une tentative de correction du chaos : $\acute{e}$tude de la fonction $f_{\mu,\lambda}\eq \mu.x.(1-x) + \lambda.x.(1+x)$}

\begin{itemize}%[label = \Alph]
\item[A] Mise en place de simplification et $\acute{e}$tude du point fixe choisi
\item[B] Etude graphique de quelques r$\acute{e}$sultats
\end{itemize}
\end{enumerate}

\end{document}

\input{transparent_plan}


And for my emphasized titles, I have these messages of error :

! Undefined control sequence.
l.23 ...es fonctions quadratiques : $Q_{\mu}(x) \eq \mu.x.(1-x)$


and the other message is :

! Undefined control sequence.
<argument> ...e la fonction $f_{\mu,\lambda} \eq \mu.x.(1-x) + \lambda.x.(1+x) l.30 ...lambda} \eq \mu.x.(1-x) + \lambda.x.(1+x)  Please, can somebody help me to understand this situation ? • Welcome to TeX.SX! When you look at an error message like that, the macro (control sequence) that is undefined is that last one before the line break, in this case \eq. What should it represent? May 12, 2016 at 8:05 • why are you using math mode for e-acute? May 12, 2016 at 8:14 • In other words, \eq is not defined so latex don't know what to do with this macro. It seems you might have copy-paste your code and forgot to also copy-past the definition of \eq (\newcommand{\eq}{...}) or load the relevant package. (By the way, using \usepackage[utf8]{inputenc} instead of \usepackage[latin1]{inputenc} will enable you to directly type é instead of $\acute{e}$ or \'{e}!) May 12, 2016 at 8:15 • Welcome, for a start a more modern class than slides might be a good idea? You can try out beamer. May 12, 2016 at 8:15 • Typing = is shorter than \eq ;-) If you want to have an equal sign, of course. May 12, 2016 at 8:16 ## 2 Answers Based on previous comments, here is a 'debugged' version of your code: \documentclass[a4paper,12pt,landscape]{slides} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage[frenchb]{babel} \usepackage{lmodern} \usepackage{calc} \usepackage{enumitem} \title{Dynamique des fonctions et le problème du chaos} \begin{document} \maketitle \textit{Problématique : } Pouvons-nous trouver une manière de corriger la composante chaotique d'un système ? \begin{enumerate} \item \emph{Introduction au chaos : la famille des fonctions quadratiques :$Q_{\mu}(x) = \mu.x.(1-x)$} \begin{itemize}%[label = \Alph*] \item[A] Début d'analyse : points fixes attracteurs \item[B] Apparition du chaos, définitions \end{itemize} \item \emph{Une tentative de correction du chaos : étude de la fonction$f_{\mu,\lambda} = \mu.x.(1-x) + \lambda.x.(1+x)$} \begin{itemize}%[label = \Alph] \item[A] Mise en place de simplification et étude du point fixe choisi \item[B] Etude graphique de quelques résultats \end{itemize} \end{enumerate} \end{document}  Modifications: • replace $\acute{e}$ by é and $\grave{e}$ by è • include \maketitle • replace \eq by = • delete \input{transparent_plan} : since it appears after \end{document}, it won't be interpreted and is thus useless. However, as pointed out by Johannes_B, the beamer class might me more indicated in your case. You can define your slides as following, and automatically generate a handout. Here is thus an 'improved' version of your original code, using beamer. (Note that I don't use fames, nor layer, what would make the presentation more dynamic) \documentclass[a4paper,12pt]{beamer} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage[frenchb]{babel} \usepackage{lmodern} \usepackage{geometry} \geometry{hmargin=1.5cm,vmargin=1.5cm} \usepackage{calc} %\usepackage{enumitem} \title{Dynamique des fonctions et le problème du chaos} \begin{document} \begin{frame} \titlepage \end{frame} \begin{frame} \frametitle{Un titre} \emph{Problématique : } % \emph is better than \textit since it describes "what" you want to do, and not "how" (for "how, trust LaTeX !) Pouvons-nous trouver une manière de corriger la composante chaotique d'un système ? \begin{enumerate} \item \emph{Introduction au chaos : la famille des fonctions quadratiques :$Q_{\mu}(x) = \mu.x.(1-x)$} \begin{enumerate}[A.] \item Début d'analyse : points fixes attracteurs \item Apparition du chaos, définitions \end{enumerate} \item \emph{Une tentative de correction du chaos : étude de la fonction$f_{\mu,\lambda} = \mu.x.(1-x) + \lambda.x.(1+x)$} \begin{enumerate}[A.] \item Mise en place de simplification et étude du point fixe choisi \item Etude graphique de quelques résultats \end{enumerate} \end{enumerate} \end{frame} \end{document}  To generate a handout, just replace the first line by: \documentclass[a4paper,12pt,handout]{beamer} \usepackage{pgfpages} \pgfpagesuselayout{2 on 1}[a4paper,border shrink=5mm]  • I'd remove geometry from the beamer version. Edit: and if one wants an aspectratio closer to that of A4, aspectratio=32 in the class options. May 12, 2016 at 9:01 You can directly type accented letters in your code, with the utf8 input encoded (even accented capital letters – cf Etude vs Étude). This encoding is known to all modern systems. Also, I replaced \eq with =, . with \cdot for multiplication dots, and the clumsy itemize environments with \item[A] &c. with a simple nested enumerate: \documentclass[a4paper,12pt,landscape, french]{slides} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage{babel} \usepackage{lmodern} \usepackage{geometry} \geometry{hmargin=1.5cm,vmargin=1.5cm} \usepackage{calc} \usepackage{enumitem} \begin{document} % \title{Dynamique des fonctions et le problème du chaos} \textit{Problématique : } Pouvons-nous trouver une manière de corriger la composante chaotique d'un système ? \begin{enumerate} \item \emph{Introduction au chaos : la famille des fonctions quadratiques :$Q_{\mu}(x) = \mu\cdot x\cdot (1-x)$} \begin{enumerate}[label = \Alph*] \item Début d'analyse : points fixes attracteurs \item Apparition du chaos, définitions \end{enumerate} \item \emph{Une tentative de correction du chaos : étude de la fonction$f_{\mu,\lambda} = \mu\cdot x\cdot (1-x) + \lambda\cdot x\cdot (1+x)\$}

\begin{enumerate}[label = \Alph*]
\item Mise en place de simplification et étude du point fixe choisi
\item Étude graphique de quelques résultats
\end{enumerate}
\end{enumerate}

\end{document}
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