2

I understand that environments such as equation would not allow page break while align will.

But I want an equation box that only comes with one equation number and it spans over multiple pages. How do I do that?

| improve this question | | | | |
  • 1
    \allowdisplaybreaks in preamble combined with eg multline or gather+ aligned environments. – JPi Oct 29 '15 at 7:05
1

A solution with a new environment, where you just specify the line where you want the equation number:

\documentclass{article}

\usepackage[a6paper,textheight=4cm]{geometry} % just for the example
\usepackage{amsmath}
\allowdisplaybreaks

\makeatletter
\newcounter{longaligned}
\newenvironment{longaligned}[1][]
 {%
  \stepcounter{longaligned}%
  \refstepcounter{equation}%
  \label{longaligned@\thelongaligned}%
  #1%
  \start@align\@ne\st@rredtrue\m@ne % start align*
 }
 {\endalign}
\newcommand{\longalignedtag}{\tag{\ref{longaligned@\thelongaligned}}}
\makeatother

\begin{document}

\begin{longaligned}
a &=b \\
c &= a+b \\
d &= h+u+j+k \\
r +e &= t + e+ r + r\\
a &=b \\
c &= a+b \\
d &= h+u+j+k \\
r +e &= t + e+ r + r\longalignedtag\\
a &=b \\
c &= a+b \\
d &= h+u+j+k \\
r +e &= t + e+ r + r
\end{longaligned}

\end{document}

It's easy to manually adjust the position of one command, than using several \notag commands; the disadvantage is that this requires two steps for synchronization, but it shouldn't be a real problem.

enter image description here

A different solution based on the same idea:

\documentclass{article}

\usepackage[a6paper,textheight=4cm]{geometry} % just for the example
\usepackage{amsmath}
\allowdisplaybreaks

\makeatletter
\newcounter{longaligned}
\newenvironment{longaligned}
 {%
  \stepcounter{longaligned}%
  \refstepcounter{equation}%
  \label{longaligned@\thelongaligned}%
  #1%
  \par\textbf{Equation block \eqref{longaligned@\thelongaligned}}
  \start@align\@ne\st@rredtrue\m@ne % start align*
 }
 {\endalign}
\makeatother

\begin{document}

\begin{longaligned}
a &=b \\
c &= a+b \\
d &= h+u+j+k \\
r +e &= t + e+ r + r\\
a &=b \\
c &= a+b \\
d &= h+u+j+k \\
r +e &= t + e+ r + r\\
a &=b \\
c &= a+b \\
d &= h+u+j+k \\
r +e &= t + e+ r + r
\end{longaligned}

\end{document}

enter image description here

If you prefer, you can easily add “End of equation block” at the bottom.

In both cases, calling the environment as

\begin{longaligned}[\label{xyz}]

will allow to use \eqref{xyz} for referring to the block.

| improve this answer | | | | |
3

You can use lot of \notag s:

\documentclass{article}
\usepackage{amsmath}
\setlength{\textheight}{4cm}  %% just for this example
\allowdisplaybreaks
\begin{document}
  \begin{align}
      a &=b \notag\\
      c &= a+b \notag\\
      d &= h+u+j+k \notag\\
      r +e &= t + e+ r + r\notag\\
      a &=b \notag\\
      c &= a+b \notag\\
      d &= h+u+j+k \notag\\
      r +e &= t + e+ r + r\\
      a &=b \notag\\
      c &= a+b \notag\\
      d &= h+u+j+k \notag\\
      r +e &= t + e+ r + r\notag
  \end{align}
\end{document}

enter image description here

But this is not a good idea to have many equations spanning more than one page with one equation number. Have some mercy on the readers.

| improve this answer | | | | |
  • It's for derivations that spans for more than a page. It wouldn't be appropriate to assign multiple equation numbers. And I am writing a report, where I am instructed to give a number to each and whatever equation block. – Argyll Oct 29 '15 at 8:16
  • Btw, if align is the solution, why not use align* and apply a single label? – Argyll Oct 29 '15 at 8:17
  • @Argyll: You can use anything appropriate. Mine was a blind shot as I had no idea of the nature of the equation/s. With align*, you have to step up the equation counter yourself. – user11232 Oct 29 '15 at 8:18
  • Or just use align* and a suitably crafted \tag. Exercise for the reader. ;-) – egreg Oct 29 '15 at 8:46

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.