我遇到了!Undefined control sequence以下解释的错误消息，无法弄清楚我做错了什么。我正在使用 Mactex 和 Texmaker。我是 LaTeX 新手，非常感谢您的帮助！
! Undefined control sequence.
\beamer@doifinframe ...\par \begin {equation*} \x
(k) = \left ( \begin {arra...
l.123 \end{frame}
%
The control sequence at the end of the top line
of your error message was never \def'ed. If you have
misspelled it (e.g., `\hobx'), type `I' and the correct
spelling (e.g., `I\hbox'). Otherwise just continue,
and I'll forget about whatever was undefined.
! Missing $ inserted.
<inserted text>
$
l.123 \end{frame}
%
I've inserted a begin-math/end-math symbol since I think
you left one out. Proceed, with fingers crossed.
! Missing } inserted
-------
代码：
\documentclass[notes=show,beamer,t,notheorems]{beamer}
\usepackage{amsfonts}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{mathpazo}
\usepackage{hyperref}
\usepackage{subfigure}
\usepackage{tikz}
\setcounter{MaxMatrixCols}{10}
\newenvironment{stepenumerate}{\begin{enumerate}[<+->]}{\end{enumerate}}
\newenvironment{stepitemize}{\begin{itemize}[<+->]}{\end{itemize} }
\newenvironment{stepenumeratewithalert}{\begin{enumerate}[<+-| alert@+>]}{\end{enumerate}}
\newenvironment{stepitemizewithalert}{\begin{itemize}[<+-| alert@+>]}{\end{itemize} }
\newtheorem{assumption}{Assumption}
\newtheorem{proposition}{Proposition}
\usetheme{CambridgeUS}
\setbeamertemplate{navigation symbols}{}
\numberwithin{figure}{section}
\setbeamertemplate{navigation symbols}{}
\useoutertheme{umbcfootline}
\setfootline{ \hfill \insertframenumber}
\numberwithin{figure}{section}
\input{tcilatex}
\renewcommand{\QTR}[2]{\frametitle{#2}}
\begin{document}
\begin{equation*}
\x(k) = \left(
\begin{array}{c}
x_1(k)\\
x_2(k)\\
\vdots\\
\end{array} \right)
\end{equation*}
答案1
\x未定义。您可能希望在 之前使用x(k) = \left(而不是。\x(k) = \left(\begin{array}