548. LaTeX技巧109：常见的三角矩阵的输入

演示代码：

\documentclass[12pt,a4paper]{article}
\usepackage{amsmath}
\usepackage{amsthm}% better theorem environments
\usepackage{times}
\usepackage{mathptmx}
\setlength\textwidth{207.0pt}
\begin{document}
\begin{align*}
\left(\begin{array}{cccc}
a_{11} & a_{12} & \cdots & a_{1n} \\
&a_{22}& \cdots &a_{2n}\\
&& \ddots & \vdots \\
\multicolumn{2}{c}{\raisebox{1.3ex}[0pt]{\Huge0}}
&&a_{nn}
\end{array}\right)
\end{align*}
\end{document}