# Matrix in TikZ and Equation

The following code draw the matrix I want:

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{matrix,decorations.pathreplacing, calc, positioning}
\begin{document}
\begin{tikzpicture}
\matrix [matrix of math nodes,left delimiter=(,right delimiter=),row sep=0.1cm,column sep=0.1cm] (m) {
1 & *     &   *  & \dots & *   & 0 & \dots & 0 \\
0 & \pm 1 &   *  & \dots & *   & 0 & \dots & 0 \\
0 & 0     &\pm 1 & \dots & *   & 0 & \dots & 0 \\
\vdots & \vdots & \vdots & \ddots & \vdots & \vdots & \ddots & \vdots\\
0 &  0    & 0    &   \dots   &\pm 1& 0 & \dots & 0 \\
0 &  0    & 0    &  \dots   & 0  & * & \dots & * \\
\vdots & \vdots & \vdots & \ddots & \vdots & \vdots & \ddots & \vdots\\
0 &  0    & 0    &   0   & 0   & * & \dots & *\\ };

\draw[dashed] ($0.5*(m-1-5.north east)+0.5*(m-1-6.north west)$) -- ($0.5*(m-8-6.south east)+0.5*(m-8-5.south west)$);

\draw[dashed] ($0.5*(m-5-1.south west)+0.5*(m-6-1.north west)$) -- ($0.5*(m-5-8.south east)+0.5*(m-6-8.north east)$);

\node[above=1pt of m-1-1] (top-1) {};
\node[above=1pt of m-1-5] (top-5) {};
\node[above=-1pt of m-1-6] (top-6) {};
\node[above=-1pt of m-1-8] (top-8) {};

\node[right=4pt of m-1-8] (right-1) {};
\node[right=4pt of m-5-8] (right-5) {};
\node[right=4pt of m-6-8] (right-6) {};
\node[right=4pt of m-8-8] (right-8) {};

\node[rectangle,above delimiter=\{] (del-top-1) at ($0.5*(top-1.south) +0.5*(top-5.south)$) {\tikz{\path (top-1.south west) rectangle (top-5.north east);}};
\node[above=10pt] at (del-top-1.north) {$k_1$};
\node[rectangle,above delimiter=\{] (del-top-2) at ($0.5*(top-6.south) +0.5*(top-8.south)$) {\tikz{\path (top-6.south west) rectangle (top-8.north east);}};
\node[above=10pt] at (del-top-2.north) {$k-k_1$};

\node[rectangle,right delimiter=\}] (del-right-1) at ($0.5*(right-1.west) +0.5*(right-5.west)$) {\tikz{\path (right-1.north east) rectangle (right-5.south west);}};
\node[right=22pt] at (del-right-1.west) {$k_1$};
\node[rectangle,right delimiter=\}] (del-right-2) at ($0.5*(right-6.west) +0.5*(right-8.west)$) {\tikz{\path (right-6.north east) rectangle (right-8.south west);}};
\node[right=22pt] at (del-right-2.west) {$k-k_1$};

\end{tikzpicture}

\end{document}


Now since I want to insert it in a equation I used the baseline option for tikz:

\documentclass{article} \usepackage{tikz} \usetikzlibrary{matrix,decorations.pathreplacing, calc, positioning} \begin{document} $$Q= \begin{tikzpicture}[baseline] \matrix [matrix of math nodes,left delimiter=(,right delimiter=),row sep=0.1cm,column sep=0.1cm] (m) { 1 & * & * & \dots & * & 0 & \dots & 0 \\ 0 & \pm 1 & * & \dots & * & 0 & \dots & 0 \\ 0 & 0 &\pm 1 & \dots & * & 0 & \dots & 0 \\ \vdots & \vdots & \vdots & \ddots & \vdots & \vdots & \ddots & \vdots\\ 0 & 0 & 0 & \dots &\pm 1& 0 & \dots & 0 \\ 0 & 0 & 0 & \dots & 0 & * & \dots & * \\ \vdots & \vdots & \vdots & \ddots & \vdots & \vdots & \ddots & \vdots\\ 0 & 0 & 0 & 0 & 0 & * & \dots & *\\ }; \draw[dashed] (0.5*(m-1-5.north east)+0.5*(m-1-6.north west)) -- (0.5*(m-8-6.south east)+0.5*(m-8-5.south west)); \draw[dashed] (0.5*(m-5-1.south west)+0.5*(m-6-1.north west)) -- (0.5*(m-5-8.south east)+0.5*(m-6-8.north east)); \node[above=1pt of m-1-1] (top-1) {}; \node[above=1pt of m-1-5] (top-5) {}; \node[above=-1pt of m-1-6] (top-6) {}; \node[above=-1pt of m-1-8] (top-8) {}; \node[right=4pt of m-1-8] (right-1) {}; \node[right=4pt of m-5-8] (right-5) {}; \node[right=4pt of m-6-8] (right-6) {}; \node[right=4pt of m-8-8] (right-8) {}; \node[rectangle,above delimiter=\{] (del-top-1) at (0.5*(top-1.south) +0.5*(top-5.south)) {\tikz{\path (top-1.south west) rectangle (top-5.north east);}}; \node[above=10pt] at (del-top-1.north) {k_1}; \node[rectangle,above delimiter=\{] (del-top-2) at (0.5*(top-6.south) +0.5*(top-8.south)) {\tikz{\path (top-6.south west) rectangle (top-8.north east);}}; \node[above=10pt] at (del-top-2.north) {k-k_1}; \node[rectangle,right delimiter=\}] (del-right-1) at (0.5*(right-1.west) +0.5*(right-5.west)) {\tikz{\path (right-1.north east) rectangle (right-5.south west);}}; \node[right=22pt] at (del-right-1.west) {k_1}; \node[rectangle,right delimiter=\}] (del-right-2) at (0.5*(right-6.west) +0.5*(right-8.west)) {\tikz{\path (right-6.north east) rectangle (right-8.south west);}}; \node[right=22pt] at (del-right-2.west) {k-k_1}; \end{tikzpicture}$$

\end{document}


Unfortunately the result is this:

What happened to the parenthesis?

• You are already using TikZ so you can remove those ugly and misaligned dots and draw it properly. Commented May 11, 2018 at 13:41
• could use a little negative \vspace above the rows with \vdots. otherwise looks good (aside from the glitch). Commented May 11, 2018 at 15:14

You're nesting tikzpictures, that is often a bad idea. Here's an alternative approach using the fit library.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{matrix,decorations.pathreplacing, calc, positioning,fit}
\begin{document}
$$Q= \begin{tikzpicture}[ baseline, label distance=10pt % added ] \matrix [matrix of math nodes,left delimiter=(,right delimiter=),row sep=0.1cm,column sep=0.1cm] (m) { 1 & * & * & \dots & * & 0 & \dots & 0 \\ 0 & \pm 1 & * & \dots & * & 0 & \dots & 0 \\ 0 & 0 &\pm 1 & \dots & * & 0 & \dots & 0 \\ \vdots & \vdots & \vdots & \ddots & \vdots & \vdots & \ddots & \vdots\\ 0 & 0 & 0 & \dots &\pm 1& 0 & \dots & 0 \\ 0 & 0 & 0 & \dots & 0 & * & \dots & * \\ \vdots & \vdots & \vdots & \ddots & \vdots & \vdots & \ddots & \vdots\\ 0 & 0 & 0 & 0 & 0 & * & \dots & *\\ }; \draw[dashed] (0.5*(m-1-5.north east)+0.5*(m-1-6.north west)) -- (0.5*(m-8-6.south east)+0.5*(m-8-5.south west)); \draw[dashed] (0.5*(m-5-1.south west)+0.5*(m-6-1.north west)) -- (0.5*(m-5-8.south east)+0.5*(m-6-8.north east)); \node[ fit=(m-1-1)(m-1-5), inner xsep=0, above delimiter=\{, label=above:k_1 ] {}; \node[ fit=(m-1-6)(m-1-8), inner xsep=0, above delimiter=\{, label=above:k-k_1 ] {}; \node[ fit=(m-1-8)(m-5-8), inner xsep=15pt,inner ysep=0, right delimiter=\}, label=right:k_1 ] {}; \node[ fit=(m-6-8)(m-8-8), inner xsep=15pt,inner ysep=0, right delimiter=\}, label=right:k-k_1 ] {}; \end{tikzpicture}$$

\end{document}

• On the cover of the TikZ & PGF manual Till Tantau himself use tikzpictures in nodes, it is probably not always so bad as the people on TeX.SX are used to say ;)
– Kpym
Commented May 11, 2018 at 14:15
• @Kpym: is not so bad if you know what you are doing, otherwise one might end up in issues like tex.stackexchange.com/q/18647/13304 ;) Commented May 11, 2018 at 15:14
• @Kpym My impression is that in most cases nesting is completely unnecessary anyway, so when it is a practice that can cause unexpected and "strange" problems if you don't know what you're doing, why not recommend against it? I don't see any nesting on the cover of the manual, by the way. (And it was Claudio who wrote that previous comment, so perhaps you should have notified him.) Commented May 13, 2018 at 8:59

Since you are loading already the decorations.pathreplacing library and make all the preparations, I could not resist using them. ;-)

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{matrix,decorations.pathreplacing, calc, positioning}
\begin{document}
$$Q= \begin{tikzpicture}[baseline] \matrix [matrix of math nodes,left delimiter=(,right delimiter=),row sep=0.1cm,column sep=0.1cm] (m) { 1 & * & * & \dots & * & 0 & \dots & 0 \\ 0 & \pm 1 & * & \dots & * & 0 & \dots & 0 \\ 0 & 0 &\pm 1 & \dots & * & 0 & \dots & 0 \\ \vdots & \vdots & \vdots & \ddots & \vdots & \vdots & \ddots & \vdots\\ 0 & 0 & 0 & \dots &\pm 1& 0 & \dots & 0 \\ 0 & 0 & 0 & \dots & 0 & * & \dots & * \\ \vdots & \vdots & \vdots & \ddots & \vdots & \vdots & \ddots & \vdots\\ 0 & 0 & 0 & 0 & 0 & * & \dots & *\\ }; \draw[dashed] (0.5*(m-1-5.north east)+0.5*(m-1-6.north west)) -- (0.5*(m-8-6.south east)+0.5*(m-8-5.south west)); \draw[dashed] (0.5*(m-5-1.south west)+0.5*(m-6-1.north west)) -- (0.5*(m-5-8.south east)+0.5*(m-6-8.north east)); \node[above=1pt of m-1-1] (top-1) {}; \node[above=1pt of m-1-5] (top-5) {}; \node[above=-1pt of m-1-6] (top-6) {}; \node[above=-1pt of m-1-8] (top-8) {}; \node[right=10pt of m-1-8] (right-1) {}; \node[right=10pt of m-5-8] (right-5) {}; \node[right=10pt of m-6-8] (right-6) {}; \node[right=10pt of m-8-8] (right-8) {}; \draw[thick,decorate,decoration=brace] (top-1.west) -- (top-5.east) node[midway,above=1mm] {k_1}; \draw[thick,decorate,decoration=brace] (top-6.west) -- (top-8.east) node[midway,above=1mm] {k-k_1}; \draw[thick,decorate,decoration=brace] (right-1.north) -- (right-5.south) node[midway,right=1mm] {k_1}; \draw[thick,decorate,decoration=brace] (right-6.north) -- (right-8.south) node[midway,right=1mm] {k-k_1}; \end{tikzpicture}$$

\end{document}