# How can I draw this matrix in Latex?

I want to draw this matrix in Latex and this is what I was trying to do but it doesn't work, I don't know how to fix it to make it look like the attached picture.

\documentclass[12pt,a4paper,intlimits,tbtags,reqno]{report}
\usepackage{tabularx}
\begin{document}
\begin{table}[ht]
\centering
\label{my-label}
$A_{n} = \left( \begin{array}{l|c|c} 2\hspace{2 em}9 & 2 & \\ 1\hspace{2 em}2 & 5\hspace{2 em}2 & \\ \cline{1-3} \hspace{2 em}3 & 7\hspace{2 em}5\hspace{2 em}2& & \\ \hspace{2 em}&3\hspace{2 em}7\hspace{2 em}5\hspace{2 em}2& \\\cline{1-3} & 3&1\hspace{2 em}9 &\\ & &5\hspace{2 em}4 \\ \end{array} \right)$
\end{table}
\end{document}

• There are many possibilities to draw that matrix, one of them could be using nicematrix package. If you see the manual, in page 3 you will find an example very similar to your image – Luis Turcio May 28 at 20:18
• What manual are you talking about? please i do not understand where i have to look, can be more specified where i can found this manual? Thanks in advance. – Angelina Maria May 28 at 20:28
• You can write texdoc nicematrix in a command line or search in ctan. After doing the last one here is the link for the manual ctan.org/pkg/nicematrix – Luis Turcio May 28 at 20:31
• ok, i will do that, thank you so much. – Angelina Maria May 28 at 20:32

## 2 Answers

I'm not sure why you have your matrix within a table. How about this:

\documentclass[12pt]{article}

\usepackage{amsmath}
\usepackage{amssymb}

\begin{document}

\begin{equation*}
A_{n} = \left(
\begin{array}{cc|cccccc|cc}
2 & 9 & 2 &&&&&&&\\
1 & 2 & 5 & 2&&&&&&\\
\hline
& 3 & 7 & 5 & 2 &&&&&\\
&& 3 & 7 & 5 & 2 &&&&\\
&&& 3 & 7 & 5 & 2 &&&\\
&&&& \cdots & \cdots & \cdots & \cdots &&\\
&&&&&& 3 & 7 & 5 & 2\\
\hline
&&&&&&& 3 & 1 & 9\\
&&&&&&&& 5 & 4
\end{array}
\right)
\end{equation*}

\end{document}


• You are Genius! Thank you so so much, I've been trying to write it for two days and I can't and I gave up but now you saved me. And I don't know about the table either, why it should be a table considering that it is a Toeplitz matrix that can be written without a table, but I think it's written that way to separate the numbers so that it can be seen better, I don't see another explanation . – Angelina Maria May 28 at 21:07
• Your welcome, glad I could help! – mcarchmiller May 28 at 21:09
• Why \hline{}? The braces serve no purpose and in other contexts they might be dangerous: try \begin{array}{cc} 1 & 2 \\ \hline{} \multicolumn{2}{c}{123} \end{array} – egreg May 28 at 21:39
• Good choice using \cdots. This looks better than the original. – barbara beeton May 28 at 23:39
• @mcarchmiller I put {} to show that an error may ensue if they're used. – egreg Jun 1 at 15:18

Like this?

\documentclass[12pt,a4paper,intlimits,tbtags,reqno]{report}
\usepackage{array}

\begin{document}

\begin{table}[ht]
\centering\setlength{\arraycolsep}{8pt}
\setlength{\extrarowheight}{2pt}
\label{my-label}
$A_{n} = \left( \begin{array}{cc|*{6}{c}|cc} 2 & 9 & 2 & & & & & \\ 1 & 2 & 5 & 2 & & & & \\ \hline & 3 & 7 & 5 & 2 & & & \\ & & 3 & 7 & 5 & 2 & & \\ & & & 3 & 7 & 5 & 2 & \\ & & & & \multicolumn{4}{c@{}|}{\dotfill} & \\% & & & & & & 3 & 7 & 5 & 2 \\ \hline & & & & & & & 3 & 1 & 9 \\ & & & & & & & & 5 & 4 \end{array} \right)$
\end{table}

\end{document}