公式总结

Question

我正在为我的学生写一本书，我希望在每一章的末尾对该章中所有重要的方程式进行总结（包括其方程式编号、实际公式和一些关于它的解释——有点像“克拉珀龙理想气体方程”）。

有没有简单的方法可以做到这一点？或者我需要疯狂地使用标签、复制粘贴等？

Answer 1

我介绍\retaineqn{...}如何呈现但保存一个等式以供稍后重演，并\recalleqn回忆起之前保存的下一个等式（重演阶段）。

\documentclass[12pt]{article}
\newcounter{retained}\setcounter{retained}{0}
\newcounter{shown}\setcounter{shown}{0}
\newcounter{saveequation}
\newcommand\retaineqn[1]{%
  \addtocounter{retained}{1}%
  \expandafter\edef\csname defeqnum\roman{retained}\endcsname{%
                                                 \arabic{equation}}%
  \expandafter\gdef\csname defeq\roman{retained}\endcsname{#1}%
  \csname defeq\roman{retained}\endcsname%
}
\newcommand\recalleqn{%
  \addtocounter{shown}{1}%
  \setcounter{saveequation}{\value{equation}}%
  \setcounter{equation}{\csname defeqnum\roman{shown}\endcsname}%
  \csname defeq\roman{shown}\endcsname%
  \setcounter{equation}{\value{saveequation}}%
}
\begin{document}

\section{A Chapter}

In equation~\ref{eq:first}, we present and retain an important equation.
\retaineqn{%
\begin{equation}
\label{eq:first}
y = x
\end{equation}
}%
Then we use it in a not so important equation~\ref{eq:second}

\begin{equation}
\label{eq:second}
y = x^2
\end{equation}

Now for this next equation (equation~\ref{eq:third}), it is also important,
so we will retain it
\retaineqn{%
\begin{equation}
\label{eq:third}
y = x^3
\end{equation}
}%
 and use it to prove this last unimportant equation

\begin{equation}
\label{eq:fourth}
y = x^4
\end{equation}

\subsection{Recapitulation}

Our first retained equation was

\recalleqn

Our next retained equation was

\recalleqn

\section{Next Section}

Did equation numbers pick up in the right place?

\begin{equation}
 y = x^5
\end{equation}

\end{document}