Putting numbered equations in the remaining space of the line

Question

I would like to define a new equation environment that displays the equation inline, but with its number being displayed at the end of the line (without text between them).

More concretely, the following code:

The quick brown fox jumps over the lazy dog. We have
\begin{equation-inline}
 a + b + c = d.
\end{equation-inline}
Therefore, ...

should output something like this:

Motivation: I am writing a document with some space constraints and I would be able to save a few lines by replacing some display-style centered equations with the above.

There have been quite a lot of questions on labeled inline equations, for example this one or this one, but my question is a bit different: I would like the equation number to be displayed at the end of the line so that it can be easily located.

Thank you in advance for your help!

Update:

With the following definition of equation-inline, the equation is displayed correctly but referencing to it doesn't work:

\documentclass{article}
\usepackage{amsmath}
\newenvironment{equation-inline}{$\stepcounter{equation}}{$\hfill(\theequation)\}
\begin{document}
The quick brown fox jumps over the lazy dog. We have
    \begin{equation-inline}\label{eq:x}
        a + b + c = d.
    \end{equation-inline}
According to~\eqref{eq:x}, we have...
\end{document}

Update 2:

Replacing \stepcounter{equation} in the above with \refstepcounter{equation} works (credit):

\newenvironment{equation-inline}{
    % Put \refstepcounter at the beginning, because
    % package `hyperref' sets the anchor here.
    \refstepcounter{equation}%
    $}{
    $\hfill(\theequation)\\}

@Zarko I would need the equation number so that I can refer to it later in the document. — f10w, May 20 '21 at 11:01
@Zarko I'm able to make it work now, but not sure if that's the optimal solution. — f10w, May 20 '21 at 11:15

score 1 · Answer 1 · answered May 20 '21 at 11:24

Although I disagree stylistically, this is how you could do it:

\documentclass[fleqn]{article}
\usepackage{amsmath}
\newcommand\inlineTag{%
    \refstepcounter{equation}%
    \hspace{0em plus 1fill}\makebox{(\theequation)}%
}
\begin{document}
\section{Option 1 (the manual way)}
The quick brown fox jumps over the lazy dog.
%
\begingroup
    \setlength{\mathindent}{0pt}
    \setlength{\abovedisplayskip}{0pt}
    \setlength{\belowdisplayskip}{0pt}
    \begin{equation}\label{option1}
        \text{The quick brown fox jumps over the lazy dog. We have }    a + b + c = d.
    \end{equation}
\endgroup
Therefore, ...
\begin{equation}
    a^2+b^2=c^2
\end{equation}

\noindent
The inline equation is \eqref{option1}.

\section{Option 2 (the automatic way)}

The quick brown fox jumps over the lazy dog.\\
The quick brown fox jumps over the lazy dog. We have $a + b + c = d.$ \inlineTag\label{option2}\\
Therefore, ...

\begin{equation}
    a^2+b^2=c^2
\end{equation}

\noindent
The inline equation is \eqref{option2}.


\end{document}

Credit for the right align code to this answer.

Thanks and +1. Option 1 is not interesting to me, while Option 2 is quite similar to my solution (I prefer using an environment because then I can switch easily between equation and equation-inline). — f10w, May 20 '21 at 11:31
You shouldn't leave a blank line before a display; it will foul up the vertical spacing and will allow a page break. And if the text following the display is a continuation of the paragraph, you shouldn't have a blank line there either (and you won't need \noindent). — barbara beeton, May 20 '21 at 16:27

Bernard · Answer 2 · 2021-05-20T14:09:14.440

1

It can be done with the linegoal package, which measures the remaining space on a line (requires two compilations), and nccmath:

\documentclass{article}
\usepackage{linegoal}
\usepackage{nccmath}
\usepackage{lipsum}
\newenvironment{inlineequation}{%
\minipage{\linegoal}\useshortskip\fleqn[0.5em]\equation}{\endequation\endfleqn\endminipage\linebreak}
\begin{document}
\noindent The quick brown fox jumps over the lazy dog. We have
\begin{inlineequation}
 a + b + c = d.
\end{inlineequation}
\lipsum[11]
\end{document}

edited May 20 '21 at 14:09

answered May 20 '21 at 12:25

Bernard

271,350

Interesting solution. Thanks! – f10w May 20 '21 at 14:03

score 0 · Answer 3 · answered May 20 '21 at 11:20

0

The following does the job:

\newenvironment{equation-inline}{
    % Put \refstepcounter at the beginning, because
    % package `hyperref' sets the anchor here.
    \refstepcounter{equation}%
    $}{
    $\hfill(\theequation)\\}

answered May 20 '21 at 11:20

f10w

791

Putting numbered equations in the remaining space of the line

3 Answers3