# A vertically centered equation number on a multline environment

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?

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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 8:06

What you want is the multlined environment provided by mathtools:

\documentclass{article}
\usepackage{mathtools}

\begin{document}

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

\end{document}


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Try to use this:

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

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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,

$$\begin{split} a+b+c+{}&d=\\ &e+f+g+h \end{split}$$


serves to have the e of the second line be placed exactly below the d` of the first line.

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