定理中的图形编号

Question

我有很多定理，其中有一些图，我必须根据各自的定理编号对它们进行编号。原则上，这适用于\numberwithin{figure}{Theorem}。但是，如果我在定理中只有一个图（例如在定理 1 中），我只希望它被称为“图 1”而不是“图 1.1”。有办法吗？

以下是示例代码：

\documentclass{article}

\usepackage{amsmath} 
\newtheorem{Theorem}{Theorem}
\numberwithin{figure}{Theorem}

\begin{document}

\begin{Theorem}
This is Theorem 1.

\begin{figure}[htp]
  \centering Figure
  \caption{This should be Figure 1 (instead of Figure 1.1).}
\end{figure}
\end{Theorem}

\begin{Theorem}
This is Theorem 2.

\begin{figure}[htp]
  \centering Figure
  \caption{This is Figure 2.1.}
\end{figure}


\begin{figure}[htp]
  \centering Figure
  \caption{This is Figure 2.2.}
\end{figure}
\end{Theorem}

\end{document}

Answer 1

由于与图形相关的图形不能“浮动”（在 LaTeX 特定意义上），您可能不应该一figure开始就为这些图形使用环境。相反，使用minipage环境和\captionof{figure}{...}语句来创建类似图形的标题。最后，对于那些具有多个图形的定理，发出指令

\counterwithin{figure}{Theorem}

在定理环境开始之前

\counterwithout{figure}{Theorem}

环境结束后立即。

\documentclass{article}
\usepackage{caption}
\usepackage{amsthm}
\newtheorem{Theorem}{Theorem}

\begin{document}

\begin{Theorem}
This is Theorem 1.

\noindent\begin{minipage}{\textwidth}\upshape
  \centering 
  Figure
  \captionof{figure}{This is Figure 1.}
\end{minipage}
\end{Theorem}

\counterwithin{figure}{Theorem}

\begin{Theorem}
This is Theorem 2.

\noindent\begin{minipage}{\textwidth}\upshape
  \centering 
  Figure
  \captionof{figure}{This is Figure 2.1.}

  \bigskip
   Figure
  \captionof{figure}{This is Figure 2.2.}
\end{minipage}
\end{Theorem}

\counterwithout{figure}{Theorem}

\begin{Theorem}
This is Theorem 3.

\noindent\begin{minipage}{\textwidth}\upshape
  \centering 
  Figure
  \captionof{figure}{This is Figure 3.}
\end{minipage}
\end{Theorem}

\end{document}