# how can I get the thicker x symbol like the following picture?

I try the \boldsymbol{\times}, but it doesn't look right.

It is bit heavy, but highly customizable.... using tikz:

\documentclass{article}
\usepackage{amsmath}
\usepackage{tikz}
\usetikzlibrary{shapes.misc}
\newcommand{\mytimes}{ \tikz[baseline=-.55ex] \node [inner sep=0pt,cross out,draw,line width=1pt,minimum size=1ex] (a) {};}
\begin{document}
$\begin{bmatrix} \times & \mytimes \\ \mytimes & \times \end{bmatrix}$
\end{document}

Here is one with bm:

\documentclass{article}
\usepackage{amsmath}
\usepackage{bm}
\begin{document}
$\begin{bmatrix} \times & \bm{\times} \\ \bm{\times} & \times \end{bmatrix}$
\end{document}

• The first solution looks very good. Thank you very much. – Yulong Ao Oct 12 '14 at 4:37
• The first solution looks very good. Thank you very much. – Yulong Ao Oct 12 '14 at 4:38