# How do I draw the following matrix in LaTeX?

I want to draw the following matrix in LaTeX:

I found that I should use the TikZ package, and I have spent a lot of time looking at the package. However, I have no experience of using the package before, and I do not know how to draw it. How can I do it?

Just arrays:

\documentclass{article}
\usepackage{amsmath,array}

\begin{document}


\end{document}


I locally defined a few commands to ease input.

• Is it possible to make the parentheses curver/more curve? – Ooker Nov 19 '18 at 1:51

Welcome to TeX.SE! Actually, you do not need TikZ for this.

\documentclass{article}
\usepackage{amsmath}
\begin{document}
$\left(\begin{array}{|*{5}{ccccc|}} \hline & & & & & 1 & & & & & & & & & & & & & & & & & & & \\ & & & & & 2 & & & & & & & & & & & & & & & & & & & \\ & & & & & \vdots & & & & & & & & & & & & & & & & & & & \\ & & & & & \vdots & & & & & & & & & & & & & & & & & & & \\ & & & & & \widehat{N} & & & & & & & & & & & & & & & & & & & \\ \hline & & & & \widehat{N} & & & & & & 1 & & & & & & & & & & & & & & \\ & & & & \vdots & & & & & & 2 & & & & & & & & & & & & & & \\ & & & & \vdots & & & & & & \vdots & & & & & & & & & & & & & & \\ & & & & 2 & & & & & & \vdots & & & & & & & & & & & & & & \\ & & & & 1 & & & & & & \widehat{N} & & & & & & & & & & & & & & \\ \hline & & & & & & & & & \widehat{N} & & & & & & 1 & & & & & & & & & \\ & & & & & & & & & \vdots & & & & & & 2 & & & & & & & & & \\ & & & & & & & & & \vdots & & & & & & \vdots & & & & & & & & & \\ & & & & & & & & & 2 & & & & & & \vdots & & & & & & & & & \\ & & & & & & & & & 1 & & & & & & \widehat{N} & & & & & & & & & \\ \hline & & & & & & & & & & & & & & & & & \bullet & & & & & & & \\ & & & & & & & & & & & & & & & & & & \bullet & & & & & & \\ & & & & & & & & & & & & & & & \bullet & & & & \bullet & & & & & \\ & & & & & & & & & & & & & & & & \bullet & & & & & & & & \\ & & & & & & & & & & & & & & & & & \bullet & & & & & & & \\ \hline & & & & & & & & & & & & & & & & & & & \widehat{N} & & & & & \\ & & & & & & & & & & & & & & & & & & & \vdots & & & & & \\ & & & & & & & & & & & & & & & & & & & \vdots & & & & & \\ & & & & & & & & & & & & & & & & & & & 2 & & & & & \\ & & & & & & & & & & & & & & & & & & & 1 & & & & & \\ \hline \end{array}\right)$
\end{document}


However, you could use TikZ to improve the appearance.

\documentclass{article}
\usepackage{amsmath}
\usepackage{tikz}
\usetikzlibrary{tikzmark}
\tikzset{% https://tex.stackexchange.com/a/156990/121799
dots/.style args={#1per #2}{%
line cap=round,
dash pattern=on 0 off #2/#1
}
}
\begin{document}
$\left(\begin{array}{|*{5}{ccccc|}} \hline & & & & & 1 & & & & & & & & & & & & & & & & & & & \\ & & & & & \tikzmarknode{21}{2} & & & & & & & & & & & & & & & & & & & \\ & & & & & & & & & & & & & & & & & & & & & & & & \\ & & & & & & & & & & & & & & & & & & & & & & & & \\ & & & & & \tikzmarknode{N1}{\widehat{N}} & & & & & & & & & & & & & & & & & & & \\ \hline & & & & \tikzmarknode{N2}{\widehat{N}} & & & & & & 1 & & & & & & & & & & & & & & \\ & & & & & & & & & & \tikzmarknode{23}{2} & & & & & & & & & & & & & & \\ & & & & & & & & & & & & & & & & & & & & & & & & \\ & & & & \tikzmarknode{22}{2} & & & & & & & & & & & & & & & & & & & & \\ & & & & 1 & & & & & & \tikzmarknode{N3}{\widehat{N}} & & & & & & & & & & & & & & \\ \hline & & & & & & & & & \tikzmarknode{N4}{\widehat{N}} & & & & & & 1 & & & & & & & & & \\ & & & & & & & & & & & & & & & \tikzmarknode{25}{2} & & & & & & & & & \\ & & & & & & & & & & & & & & & & & & & & & & & & \\ & & & & & & & & & \tikzmarknode{24}{2} & & & & & & & & & & & & & & & \\ & & & & & & & & & 1 & & & & & & \tikzmarknode{N5}{\widehat{N}} & & & & & & & & & \\ \hline & & & & & & & & & & & & & & & & & \bullet & & & & & & & \\ & & & & & & & & & & & & & & & & & & \bullet & & & & & & \\ & & & & & & & & & & & & & & & \bullet & & & & \bullet & & & & & \\ & & & & & & & & & & & & & & & & \bullet & & & & & & & & \\ & & & & & & & & & & & & & & & & & \bullet & & & & & & & \\ \hline & & & & & & & & & & & & & & & & & & & \tikzmarknode{N6}{\widehat{N}} & & & & & \\ & & & & & & & & & & & & & & & & & & & & & & & & \\ & & & & & & & & & & & & & & & & & & & & & & & & \\ & & & & & & & & & & & & & & & & & & & \tikzmarknode{26}{2} & & & & & \\ & & & & & & & & & & & & & & & & & & & 1 & & & & & \\ \hline \end{array}\right)$
\begin{tikzpicture}[overlay,remember picture]
\foreach \X in {1,...,6}
{\draw[very thick, dots=8 per 1cm,shorten >=3pt,shorten <=3pt] (2\X) -- (N\X);}
\end{tikzpicture}
\end{document}


ADDENDUM: In an attempt to make Ryan Reich a bit happy, here is a version in which you only have to specify the nonempty entries of this sparse array. These entries are determined by the list {6/1/1,6/2/2,6/5/\widehat{N},... }, where each entry has the structure <X>/<Y>/<entry> with X and Y specifying the position. Notice that one could shorten this further if you really have only one type of columns, but the point here is to allow to build arbitrary sparse matrices of that type. This code uses this answer.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{matrix,calc}
\usepackage{etoolbox}
\tikzset{% https://tex.stackexchange.com/a/156990/121799
dots/.style args={#1per #2}{%
line cap=round,
dash pattern=on 0 off #2/#1
}
}
\begin{document}
\edef\mylist{6/1/1,6/2/2,6/5/\widehat{N},%
5/6/\widehat{N},5/9/2,5/10/1,%
11/6/1,11/7/2,11/10/\widehat{N},%
10/11/\widehat{N},10/12/2,10/15/1,%
16/11/1,16/12/2,16/15/\widehat{N},%
20/21/\widehat{N},20/22/2,20/25/1%
}
\begin{tikzpicture}
\let\mymatrixcontent\empty
\foreach \Y in {1,...,25}{%
\foreach \X in {1,...,25}
{\xdef\tmp{{}}
\foreach \XX/\YY/\ZZ in \mylist
{\ifnum\XX=\X
\ifnum\YY=\Y
\xdef\tmp{\ZZ}
\fi
\fi}
\ifnum\X=25
\expandafter\gappto\expandafter\mymatrixcontent\expandafter{\tmp\space\\}%
\else
\expandafter\gappto\expandafter\mymatrixcontent\expandafter{\tmp\space\&\space}%
\fi
}
}
\matrix [matrix of math nodes,ampersand replacement=\&,left delimiter=(,
right delimiter=),draw,row sep=3pt] (mat) {
\mymatrixcontent
};
\foreach \X [evaluate=\X as \Y using {int(\X+1)}]in {5,10,...,20}
{\coordinate (aux1) at ($(mat-1-\Y.west)!0.5!(mat-1-\X.east)$);
\coordinate (aux2) at (mat-\X-1.south);
\draw (mat.north -| aux1) -- (mat.south -| aux1)
(mat.west |- aux2) -- (mat.east |- aux2);}
\foreach \X/\Y [evaluate=\Y as \Z using {int(\Y+3)}] in
{6/2,5/6,11/7,10/12,16/12,20/22}
{\draw[very thick, dots=8 per 1cm,shorten >=3pt,shorten <=3pt]
(mat-\Y-\X) -- (mat-\Z-\X);}
\draw[line width=1.2mm, dots=4 per 1cm]
(mat-16-18.center) -- (mat-18-20.center)
(mat-18-16.center) -- (mat-20-18.center);
\end{tikzpicture}
\end{document}


• I don't want to be a jerk, but filling a page with ampersands that require careful counting is not a very helpful answer. – Ryan Reich Nov 19 '18 at 1:06
• @RyanReich Are you really typing them one by one? If so, then I agree. But of course if you just do copy and paste, then it is not that cumbersome. Well, and if you like phantoms better (and make sure that none of the entries exceeds the size of those), I'd say this is a matter of taste, but otherwise it is a bit nontrivial to bet things aligned across different blocks. So that is just to say that I definitely did not have to count here. – user121799 Nov 19 '18 at 2:16
• What if I make a mistake? What if I need to make a change? There may technically be a programmatic avenue into this gigantic expression but it's fragile and not apparent on the finished product. It doesn't say what it does, it just is. – Ryan Reich Nov 19 '18 at 3:48
• @RyanReich If you make a mistake, you will not get what you want. However, this is not specific to this matrix. You seem not to like this answer, which is fine. However, I do not really see the purpose of your comments. I believe to have told you why I did what I did. If you have a better solution post it. (And yes, I do now how to typeset a matrix programmatically. Do you want me to post such a solution? The OP has already made her choice...) And yes, the matrix is gigantic. – user121799 Nov 19 '18 at 3:57
• @RyanReich In an attempt to remove the tension in our exchange of opinions, I added a version in which you only need to specify the nontrivial entries. – user121799 Nov 19 '18 at 5:11