3

I am editing a rather long text which contains many equations and floats, and encountered a problem with the align and gather environments.

MWE:

\documentclass[preview]{standalone}
\usepackage{amsmath}
\begin{document}

Paragraph one. Lorem ipsum dolor sit amet, consecuteur adipiscing elit.

\begin{gather*}
 \boxed{\sum_{x=1}^{N} A_x} \\
 \boxed{\sum_{x=1}^{N} A_x}
\end{gather*}

Paragraph two. Lorem ipsum dolor sit amet, consecuteur adipiscing elit.

\end{document}

Result:

enter image description here

There is too much vertical space between the first paragraph and the equation, as if an extra empty paragraph was inserted. If I delete the blank line between the first paragraph and the math environment, there is no extra space, but the page can't be broken at that point and I often I end up with orphans. The extra space is not present when I use the equation environment or \[ \]:

\documentclass[preview]{standalone}
\usepackage{amsmath}
\begin{document}

Paragraph one. Lorem ipsum dolor sit amet, consecuteur adipiscing elit.

\[ \boxed{\sum_{x=1}^{N} A_x} \]
\[ \boxed{\sum_{x=1}^{N} A_x} \]

Paragraph two. Lorem ipsum dolor sit amet, consecuteur adipiscing elit.

\end{document}

Result:

enter image description here

How can I get rid of the unwanted vertical space, but at the same time allow page breaks before the environment?

Improve this question
3
  • 4
    Pages should never start with a displayed equation, if it's not a continuation of a display from the previous page. You can allow breaks inside alignment displays by issuing \allowdisplaybreaks in the document preamble, but never leave a blank line before a display.
    – egreg
    Jul 13, 2013 at 20:16
  • 1
    Why not? If I use \allowdisplaybreaks, then pages can start with fragments of equations. Why not also allow them to start with complete equations too?
    – Krzysztof Kosiński
    Jul 14, 2013 at 0:28
  • 1
    @KrzysztofKosiński -- the "edict" against starting a page with a displayed equation is based on long tradition. this is mentioned in the texbook on p.189 in the last (double-danger-sign) paragraph.
    – barbara beeton
    Aug 27, 2013 at 12:57

2 Answers 2

Reset to default
6

Pages should never start with a displayed equation that is not a continuation of a display from the previous page (and this case should be a kind of last resort).

You can automatically allow page breaks inside multiline alignment displays by issuing

\allowdisplaybreaks

(an amsmath command) in the document preamble, but TeX will never break a page before a display, unless you play some dirty trick yourself.

Never leave a blank line before a display.

Improve this answer
0

I found a solution, and no real justification for the ban on page breaks before a displayed equation was given, so I'm leaving a note to others who might see the question.

To allow a break before a specific displayed equation, but get rid of the extra vertical space, put \pagebreak[0] in place of the first blank line:

\documentclass[preview]{standalone}
\usepackage{amsmath}
\begin{document}

Paragraph one. Lorem ipsum dolor sit amet, consecuteur adipiscing elit.
\pagebreak[0]
\begin{gather*}
 \boxed{\sum_{x=1}^{N} A_x} \\
 \boxed{\sum_{x=1}^{N} A_x}
\end{gather*}

Paragraph two. Lorem ipsum dolor sit amet, consecuteur adipiscing elit.

\end{document}

To allow breaks everywhere, redefine \predisplaypenalty in the preamble:

\makeatletter
\predisplaypenalty=\@medpenalty
\makeatother

Both of these ways allow the page breaks to happen.

Improve this answer

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.