# Is it possible to pagebreak aligned equations?

The report I'm writting features a lot of long, multiple lines equations. To reduce visual polution I've been using an aligned environment nested inside equation. This way (unlike just using an align environment) I get only a single label for all the lines.

The problem is that so many long equations often need to be broken into two pages, otherwise I get lots of blank vertical space in the document. However the aligned environment does not allow the \displaybreak command.

Is there an alternative way to achieve a pagebreak inside an aligned equation?

Here's a sample ofthe equations I'm using

\begin{aligned} ...\\ ...\\ %I need to pagebreak here ...\\ \end{aligned}

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You can't break aligned; the only breakable environments are align and gather (with the *-variants). –  egreg Apr 12 '12 at 18:01
What about the split environment? –  Stephan Lehmke Apr 12 '12 at 18:05
About \begin{aligned}: Would \begin{align}...\notag \\ \label{where you want it} \\ \end{align} (or the split environment as mentioned by Stephan Lehmke) be a possible alternative for you? –  Stephen Apr 12 '12 at 18:09
@Stephen I'll try it now, but according to AucTeX split can't be broken either. align+\notag seems like a good idea. I wasn't using it because that would involve managing dozens of \notags. But I suppose I could use it only on the problematic equations. –  Malabarba Apr 12 '12 at 21:15
if you only want one number you can use the starred form of the environment and use \tag once rather than the unstarred form and use \notag on all but one line –  David Carlisle Apr 12 '12 at 22:22

First of all to allow page breaks inside equations you have to set the command \allowdisplaybreaks. Without setting this one no page break occurs.

Using a simple align-environment. Of course as @DavidCarlisle suggested you can use the star variant to suppress the numbering and set a specific tag by \tag.

The environment split can't handle page breaks.

\documentclass{article}
\usepackage{amsmath}
\usepackage{kantlipsum}
\usepackage{showframe}
\allowdisplaybreaks

\begin{document}
\kant[1-3]
\begin{align*}
a\\
b\\
c\\
d\\
e\tag{\stepcounter{equation}\theequation}\\
f\\
g\\
h\\
i
\end{align*}
\end{document}

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The tag thing is not working for me. I found this \stepcounter{equation}\tag{\theequation}\label{myeq1} working. –  Sibbs Gambling Dec 28 '14 at 9:12
It somehow solves my problem of a mildly underfull split equation...it didn't break, but fudge the spaces a little bit...why...? –  Troy Woo Feb 9 at 15:42