A vertically centered equation number on a multline environment

Question

The multline environment does exactly what I want in splitting a long formula between lines by utilizing the horizontal space to the fullest. (I don't want the alignment features of the align environment.)

The problem is, I want to vertically center the equation number, as opposed to making it appear on the second line (as it does by default).

How do I do this?

I thought that maybe \raisetag could help, but it doesn't have any effect if the tag was not shifted from it's natural position... — Jellby, Jun 26 '12 at 08:06

score 17 · Accepted Answer · edited Jun 09 '17 at 17:22

17

What you want is the multlined environment provided by mathtools:

\documentclass{article}
\usepackage{mathtools}

\begin{document}

\begin{equation}
\begin{multlined}
a+b+c+d+e+f+{}\\
g+h+i+j
\end{multlined}
\end{equation}

\end{document}

enter image description here

edited Jun 09 '17 at 17:22

David Carlisle

757,742

answered Jun 26 '12 at 09:41

egreg

1,121,712

Is there some update to have this output without mathtools, not necessarily aligning something? – Sigur Jan 15 '18 at 15:44
1

@Sigur multlined is only available with mathtools. – egreg Jan 15 '18 at 16:37
multlined doesn't use all the horizontal space as multline does. there is some alternative more similar to multline? – carlo Jan 30 '20 at 11:05

score 4 · Answer 2 · edited Jul 15 '17 at 15:53

4

Try to use this:

\begin{equation}\label{xx}
\begin{split}
 a&= b+c-d\\
  & \quad +e-f\\
  &= g+h\\
  &= i
\end{split}
\end{equation}`

edited Jul 15 '17 at 15:53

David Carlisle

757,742

answered Jun 26 '12 at 00:33

Sigur

37,330

score 2 · Answer 3 · edited Jul 15 '17 at 15:53

This answer is really just an addendum to/augmentation of the answer provided by @Thiago on the use of a split environment within an equation environment to get the vertical centering of the equation number.

Normally, one uses the split environment to align successive lines on a single common point -- frequently, not necessarily, an = sign.
However, by leaving off the align symbol, &, entirely from two (or more) consecutive lines, the resulting lines will simply be centered, one line after the other.
Other alignment possibilities exist too. For example, the following code,
```
\begin{equation} \begin{split}
a+b+c+{}&d=\\
&e+f+g+h
\end{split} \end{equation}
```
serves to have the e of the second line be placed exactly below the d of the first line.

A vertically centered equation number on a multline environment

3 Answers3

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