自定义子公式编号

Question

我需要自定义方程编号，如下所示：

Some text ...

    a+b  (5)
    3+2  (5')

... some more text....

    c+d  (6)

这个想法是 (5') 是 (5) 的一个例子。我想过使用子方程，但我不知道如何自定义内部编号，因为它会生成 5a 和 5b，或 5.i、5.ii 等……如果我改用 \tag{}，我不确定如何获取前一个方程编号（示例中为 5）。

Answer 1

您可以定义一个\eqorn命令。如果您使用，\eqorn['']您将获得两个素数；可以在可选参数中指定任何数学符号。

\documentclass{article}
\usepackage{amsmath}

\newcommand{\eqorn}[1][']{\tag{\theequation\ensuremath{#1}}}

\begin{document}

Some text ...
\begin{gather}% or align or whatnot
a+b \label{main} \\
3+2 \eqorn \label{secondary}
\end{gather}
... some more text....
\begin{equation}
c+d
\end{equation}
with references to \eqref{main} and \eqref{secondary}.

\end{document}

Answer 2

这里有一种方法，使用expl3来\prg_replicate:nn生成 的n副本以'对 中的方程进行编号，subequations并etoolbox使用\patchcmd将其插入到subequations环境中。

\documentclass{article}
\usepackage{amsmath}
\usepackage{expl3}

% Creating a command to print a number of apostrophes
\ExplSyntaxOn
\cs_new:Npn \apost #1
  { \__andy_apost:cn { c@ #1 } }
\cs_new:Npn \__andy_apost:Nn #1
  {
    \ensuremath {
      \prg_replicate:nn { #1 - 1 } { {'} }
    }
  }
\cs_generate_variant:Nn \__andy_apost:Nn { c }
\ExplSyntaxOff

% Patching-in that command in \subequations
\usepackage{etoolbox}
\patchcmd\subequations
  {\def\theequation{\theparentequation\alph{equation}}}
  {\def\theequation{\theparentequation\apost{equation}}}
  {}{\FAIL}

\begin{document}

\begin{subequations}
\begin{equation}
  a+b
\end{equation}
\begin{equation}
  3+2
\end{equation}
\begin{equation}
  5
\end{equation}
\end{subequations}

\end{document}

Answer 3

另一种方法是修改答案这里：

\documentclass{article}
\usepackage{amsmath}
\makeatletter
\newcommand*\ifcounter[1]{%
  \ifcsname c@#1\endcsname%
    \expandafter\@firstoftwo%
  \else%
    \expandafter\@secondoftwo%
  \fi%
}%
\makeatother



\newcommand\EqFamTag[2][roman]{%
\ifcounter{#2}{%
\expandafter\addtocounter{#2}{1}%
\expandafter\addtocounter{#2Prev}{1}
\xdef\temp{\csname #2 Eq\endcsname \ifnum\value{#2Prev}>0 \space(\csname #1\endcsname{#2Prev})\fi}%
\global\expandafter\let\csname #2\arabic{#2}\endcsname\temp%
\tag{\temp}%
}{%
\global\expandafter\newcounter{#2}%
\global\expandafter\newcounter{#2Prev}
\expandafter\addtocounter{#2}{1}%
\xdef\temp{\theequation \ifnum\value{#2Prev}>0 \space(\csname #1\endcsname{#2Prev})\fi}%
\xdef\eqonfamily{\theequation}%
\global\expandafter\let\csname #2 Eq\endcsname\eqonfamily%
\global\expandafter\let\csname #2\arabic{#2}\endcsname\temp%
\tag{\temp}%
\expandafter\addtocounter{equation}{1}
}%
}%

\newcommand\myFamRef[2][1]{\csname #2#1\endcsname}

\begin{document}
\section{test}
\begin{equation}
f(x)=3\cdot x
\end{equation}

\begin{equation}
    x=4\cdot y \EqFamTag{MyFamily}
\end{equation}

As an example:

\begin{equation}
    x=4\cdot 2=8\EqFamTag{MyFamily}
\end{equation}

The equation: \myFamRef[2]{MyFamily} is the first example/member of the equation \myFamRef{MyFamily}

\begin{equation}
    x=4\cdot y 
\end{equation}

Another example of :

\begin{equation}
    x=4\cdot 2=8\EqFamTag{MyFamily}
\end{equation}

The equation: \myFamRef[3]{MyFamily} is the second example/member of the equation \myFamRef{MyFamily}

Another family of equations is:

\begin{equation}
    f(x)=3+y \EqFamTag{NewFam}
\end{equation}

and a member of it is:

\begin{equation}
    f(6)=9 \EqFamTag{NewFam}
\end{equation}

\end{document}

输出：

Answer 4

很容易将第一个（主）子方程编号为普通方程，子方程标准编号仅从第二个子方程开始：

\documentclass{article}
\usepackage{amsmath}
\setcounter{equation}{4}

\begin{document}
Some text . . . . . .
\begin{subequations}
\addtocounter{equation}{-1}
\begin{gather}
  a+b \label{main} \\
  3+2 \label{ex-1} \\
  5\label{ex-2}
\end{gather}
\end{subequations}.
. . . . . .Some more text . . . . . .
\begin{equation}
  c + d
\end{equation}

\eqref{ex-1} and \eqref{ex-2} illustrate \eqref{main}.

\end{document}