# Tikzpicture and matrix

I want use tikzpicture for draw my matrix, U=[matrix], using this code

\begin{align*}
U&=
\begin{tikzpicture}[decoration=brace]
\matrix (m)[matrix of math nodes,left delimiter=[,right delimiter={]},ampersand replacement=\&] {
\dfrac{2}{N}-1 \& \dfrac{2}{N} \& \cdots \& \dfrac{2}{N} \& \cdots\& \dfrac{2}{N} \\
\vdots \& \vdots \& \ddots \& \cdots \& \vdots \& \vdots \\
\,\,\,\,\,\dfrac{2}{N}\,\,\,\, \& \dfrac{2}{N} \& \dfrac{2}{N} \& \dfrac{2}{N}-1 \& \cdots \& \dfrac{2}{N} \\
\vdots \& \vdots \& \vdots \& \vdots \& \ddots \& \vdots\\
\dfrac{2}{N} \& \dfrac{2}{N} \& \cdots \& \dfrac{2}{N} \& \cdots  \& \dfrac{2}{N}-1\\
};
\draw[decorate,transform canvas={xshift=-1.4em},thick] (m-3-1.south west) -- node[left=2pt] {$m$} (m-1-1.north west);
\draw[decorate,transform canvas={yshift=0.5em},thick] (m-1-1.north west) -- node[above=2pt] {$m$} (m-1-4.north east);
\end{tikzpicture}
\end{align*}


but I can not get align U=. How I will be able to make this?

Simply add the baseline option to tikzpicture; I also did some other modifications to improve your code (in particular, now the braces are perfectly horizontal and vertical):

\documentclass{article}
\usepackage{amsmath}
\usepackage{tikz}
\usetikzlibrary{decorations.pathreplacing,matrix}

\tikzset{
table/.style={
matrix of math nodes,
row sep=-\pgflinewidth,
column sep=-\pgflinewidth,
nodes={rectangle,text width=3em,align=center},
text depth=1.25ex,
text height=2.5ex,
nodes in empty cells,
left delimiter=[,
right delimiter={]},
ampersand replacement=\&
}
}

\begin{document}

$U= \begin{tikzpicture}[baseline,decoration=brace] \matrix (m) [table] { \dfrac{2}{N}-1 \& \dfrac{2}{N} \& \cdots \& \dfrac{2}{N} \& \cdots\& \dfrac{2}{N} \\ \vdots \& \vdots \& \ddots \& \cdots \& \vdots \& \vdots \\ \,\,\,\,\,\dfrac{2}{N}\,\,\,\, \& \dfrac{2}{N} \& \dfrac{2}{N} \& \dfrac{2}{N}-1 \& \cdots \& \dfrac{2}{N} \\ \vdots \& \vdots \& \vdots \& \vdots \& \ddots \& \vdots\\ \dfrac{2}{N} \& \dfrac{2}{N} \& \cdots \& \dfrac{2}{N} \& \cdots \& \dfrac{2}{N}-1\\ }; \draw[decorate,transform canvas={xshift=-1.4em},thick] (m-3-1.south west) -- node[left=2pt] {m} (m-1-1.north west); \draw[decorate,transform canvas={yshift=0.5em},thick] (m-1-1.north west) -- node[above=2pt] {m} (m-1-4.north east); \end{tikzpicture}$

\end{document}


And here's a TikZ-free possibility, using blkarray and bigdelim:

\documentclass{article}
\usepackage{amsmath}
\usepackage{multirow,bigdelim,blkarray}

\newcommand\overmat[3][0pt]{%
\makebox[0pt][l]{$\smash{\overbrace{\phantom{% \begin{matrix}\phantom{\rule{0pt}{#1}}#3\end{matrix}}}^{#2}}$}#3}

\begin{document}

$U = \begin{blockarray}{@{}r[cccccc]} \\[-1ex] \ldelim\{{4}{14pt}[m] & \overmat[27pt]{\textstyle m}{\dfrac{2}{N}-1 & \dfrac{2}{N} & \cdots & \dfrac{2}{N}\qquad} & \cdots& \dfrac{2}{N} \\ & \vdots & \vdots & \ddots & \cdots & \vdots & \vdots \\ & \,\,\,\,\,\dfrac{2}{N}\,\,\,\, & \dfrac{2}{N} & \dfrac{2}{N} & \dfrac{2}{N}-1 & \cdots & \dfrac{2}{N} \\ & \vdots & \vdots & \vdots & \vdots & \ddots & \vdots \\ & \dfrac{2}{N} & \dfrac{2}{N} & \cdots & \dfrac{2}{N} & \cdots & \dfrac{2}{N}-1 \\[2ex] \end{blockarray}$

\end{document}