I'm new to latex and am using some stuff from a document my professor sent out.
I'm trying to define something in a paper I'm writing. Here is what I have:
\documentclass[11pt]{amsart}
\usepackage{amssymb,latexsym,amsmath,amsthm,enumitem,hyperref}
\usepackage{graphics,graphicx,multicol,tikz,pgfplots,tkz-
euclide,relsize,framed}
\usetikzlibrary{calc}
\tikzset{fontscale/.style = {font=\relsize{#1}}}
\setlength{\topmargin}{-0.750in}
\setlength{\textheight}{9.5in}
\setlength{\textwidth}{6.5in}
\setlength{\oddsidemargin}{0in}
\setlength{\evensidemargin}{0in}
\allowdisplaybreaks
\renewcommand{\labelenumi}{(\alph{enumi})}
\renewcommand{\labelenumii}{\roman{enumii}.}
\setlength\arraycolsep{2pt}
\begin{document}
\section{Important Definitions and Theorems}
\subsection{Definition [Sparsity]}
The \emph{sparsity} of $x \in \mathbb{R}^n$ is defined by
\begin{equation}
\norm{x}_{0} = card{k \in {1, 2, . . . , n} : x_k \neq 0}
\end{equation}
\end{document}
However, when I run this I get an Undefined Control Sequence error and I'm not sure what that means or how to fix it, hence I have come for your merciful help. Thanks!
\norm
. Do you have any preference for how the norm of something should be denoted?amssymb
package, there can be no excuse or justification for loadinglatexsym
as well. Similarly, since you're loading thegraphicx
package, nothing but a high tolerance for code clutter can justify loadinggraphics
as well.