braces over matrix

Question

I want to make an overbrace and a side brace on my matrix in order to indicate its size. How can I achieve that.

  \begin{pmatrix}
  1 & 1 & 0 & .& . & . & 0 & 1  \\
  0 & 0 & 1 & .& . & . & 1 & 0 \\
 .\\
 .\\
 .\\
  0 & 1 & 1 & . & . & . & 1 & 1
 \end{pmatrix}

Answer 1

Here's one way... [EDITED, added \mkern to address barbara's concern; REEDITED to make use of \overbrace superscript]

\documentclass{article}
\usepackage{amsmath}
\usepackage{stackengine}
\begin{document}
\def\tmp{%
  \begin{pmatrix}
  1 & 1 & 0 & .& . & . & 0 & 1  \\
  0 & 0 & 1 & .& . & . & 1 & 0 \\
 .\\
 .\\
 .\\
  0 & 1 & 1 & . & . & . & 1 & 1
 \end{pmatrix}
}%
\[
\stackMath\def\stackalignment{r}%
  \stackon%
    {\mathrm{10~rows}\left\{\tmp\right.}%
    {\overbrace{\phantom{\smash{\tmp\mkern -36mu}}}^{\mathrm{\textstyle 12~columns}}\mkern 20mu}%
\]
\end{document}

Answer 2

The following requires some \nulldelimiterspace corrections, but only uses amsmath:

\documentclass{article}

\usepackage{amsmath}

\begin{document}

\def\matriximg{%
  \begin{matrix}
    1 & 1 & 0 & \cdot & \cdot & \cdot & 0 & 1 \\
    0 & 0 & 1 & \cdot & \cdot & \cdot & 1 & 0 \\
    \cdot                                     \\
    \cdot                                     \\
    \cdot                                     \\
    0 & 1 & 1 & \cdot & \cdot & \cdot & 1 & 1
   \end{matrix}
}%
\[
  \text{\scriptsize 10~rows}\left\{\left(\vphantom{\matriximg}\right.\right.\kern-2\nulldelimiterspace
  \overbrace{\matriximg}^{\text{12 columns}}\kern-\nulldelimiterspace\left.\vphantom{\matriximg}\right)
\]

\end{document}

For raising the \overbrace slightly, you could use

\vphantom{\raisebox{.25\baselineskip}{$\matriximg$}}\matriximg

Answer 3

Here is what you can do with {pNiceMatrix} of nicematrix (≥ 6.4 of 2021/11/23).

\documentclass{article}
\usepackage{nicematrix}
\begin{document}
$10$ rows $\left{
\begin{pNiceMatrix}
   1 & 1 & 0 & \cdot & \cdot & \cdot & 0 & 1 \
   0 & 0 & 1 & \cdot & \cdot & \cdot & 1 & 0 \
   \cdot                                     \
   \cdot                                     \
   \cdot                                     \
   0 & 1 & 1 & \cdot & \cdot & \cdot & 1 & 1
\CodeAfter
   \OverBrace[yshift=1.5mm,shorten]{1-1}{1-last}{12 \text{ columns}}
\end{pNiceMatrix}
\right.$
\end{document}

You need several compilations (because nicematrix uses PGF/Tikz nodes under the hood).

Answer 4

I would use a finer and cleaner option by employing the known \overbrace which allows you to achieve your results very easily.

Here is a small example

$$
\overbrace{\begin{bmatrix}
    \epsilon[1]\\
    \epsilon[2]\\
    \vdots \\
    \epsilon[M]
    \end{bmatrix}}^{a}
$$