Matrix in Latex
You must read at least lshort (page 58) or amsldoc.pdf Section 4.
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\[
\begin{bmatrix}
x_{11} & x_{12} & x_{13} & \dots & x_{1n} \\
x_{21} & x_{22} & x_{23} & \dots & x_{2n} \\
\hdotsfor{5} \\
x_{d1} & x_{d2} & x_{d3} & \dots & x_{dn}
\end{bmatrix}
=
\begin{bmatrix}
x_{11} & x_{12} & x_{13} & \dots & x_{1n} \\
x_{21} & x_{22} & x_{23} & \dots & x_{2n} \\
\vdots & \vdots & \vdots & \ddots & \vdots \\
x_{d1} & x_{d2} & x_{d3} & \dots & x_{dn}
\end{bmatrix}
\]
\end{document}
From the link @TobyStack gave:
I don't use the document/array package because I'm not very experienced.
new row:\\
(btw, you can use that for $\displaystyle\sum_{j=0\\j\ne i}^m\sum_{i=0}^n$
)
output:
new column: &
Also, use
line: \ldots
diagonal: \ddots
vertical: \vdots
output:
Depending on your preference:
brackets: \begin{bmatrix}\end{bmatrix}
parentheses: \begin{pmatrix}\end{pmatrix}
Screenshoot: