# mathtools: the use of intertext in align

If I use \intertext{some sentence or two} and then continue align, will the align environment break across a page break where the text is inserted or is it still unbreakable?

If it is still unbreakable, is there a way to make it breakable without using a new align environment and \phantom{some equation} to re-align the the alignment position.

So consider:

\documentclass{article}
\usepackage{mathtools}
\begin{document}
Suppose this text takes us just above the page breaking point (let's say 5 lines).
\begin{align*}
1 &= 1\\
2 &= 2\\
\intertext{sentence 1\\
sentence 2.}
3 &= 3\\
4 &= 4\\
5 &= 5
\end{align*}
\end{document}


If the box doesn't break, there will be a significant gap of white space which will look ugly. However, if it breaks at \intertext{}, the look will flow more natural picking up the remainder of the align environment after the page break.

• Line breaks/paragraph breaks in \intertext doesn't work, by the way. – Torbjørn T. Aug 15 '13 at 19:39

Well, a quick test shows that it can break before the \intertext. If that is insufficient, you can add \allowdisplaybreaks to allow page breaks between lines in multi-line math environments.

\documentclass[a5paper]{article}
\usepackage{mathtools}
% \allowdisplaybreaks
\begin{document}
\vspace*{8cm}
Suppose this text takes us just above the page breaking point (let's say 5 lines).
\begin{align*}
1 &= 1\\
2 &= 2\\
\intertext{sentence 1 sentence 1sentence 1 sentence 1 sentence 1.
sentence 2.}
3 &= 3\\
4 &= 4\\
5 &= 5
\end{align*}
\end{document}

• Thanks. I didn't know about allowdisplaybreaks. – dustin Aug 15 '13 at 19:37
• @dustin: See section 3.9 Vertical spacing and page breaks in multiline displays (p 8) in the amsmath documentation. – Werner Aug 15 '13 at 19:41