! Undefined control sequence. l.11 \forall

Question

I get ! Undefined control sequence. l.11 \forall n,m \gt

I don't understand why:

\documentclass[preview, border=1pt, convert={outext=.png}]{standalone}
\usepackage{amsfonts}
\usepackage{mathtools}
\usepackage{amsmath,esint}
\usepackage{amssymb}
\usepackage{siunitx}
\usepackage{braket}
\usepackage[utf8]{inputenc}
\begin{document}
\begin{equation*}
\forall n,m \gt n_{\varepsilon} \quad \Longrightarrow  \quad ||\mathbf{x}_n - \mathbf{x}_m|| \lt \varepsilon
\end{equation*}
\end{document}

score 0 · Accepted Answer · 2019-03-25T10:43:08.433

0

I think you are looking for \ge and \le. \gt and \lt are not defined.

\documentclass[varwidth]{standalone}
\usepackage{amsmath}
\begin{document}
\begin{equation*}
\forall n,m \ge n_{\varepsilon} \quad \Longrightarrow  \quad ||\mathbf{x}_n - \mathbf{x}_m|| \le \varepsilon
\end{equation*}
\end{document}

Edit 1

The > and < signs are already on your keyboard:

\documentclass[varwidth]{standalone}
\usepackage{amsmath}
\begin{document}
\begin{equation*}
\forall n,m > n_{\varepsilon} \quad \Longrightarrow  \quad ||\mathbf{x}_n - \mathbf{x}_m|| < \varepsilon
\end{equation*}
\end{document}

In case you want to use \gt or \lt, you have to define it. The definition below is taken from this answer:

\documentclass[varwidth]{standalone}
\usepackage{amsmath}
\newcommand{\lt}{\symbol{"3C}}
\newcommand{\gt}{\symbol{"3E}}
\begin{document}
\begin{equation*}
\forall n,m \lt n_{\varepsilon} \quad \Longrightarrow  \quad ||\mathbf{x}_n - \mathbf{x}_m|| \gt \varepsilon
\end{equation*}
\end{document}

edited Mar 25 '19 at 10:43

answered Mar 25 '19 at 10:33

no I don't want the equal sign – Giuliano Malatesta Mar 25 '19 at 10:34
@GiulianoMalatesta Then why don't you use > and <? – Mar 25 '19 at 10:35
that's ok. What's the difference betweem \gt \lt and > < ? – Giuliano Malatesta Mar 25 '19 at 10:40
@GiulianoMalatesta \gt and \lt are not already defined. I think you are following this answer or something similar, but you should make sure that \newcommands are included. IMHO you should just use > and <. We should not make things more complicated. – Mar 25 '19 at 10:43

! Undefined control sequence. l.11 \forall

1 Answers1

Edit 1