[Tex/LaTex] Equation at page break forces widow line from previous paragraph

equationspage-breakingparagraphswidows-orphans

I have a two-column document, and I'm having some weird behavior at an automatic page break.
I have some text followed by some equations like this:

So that abutting triangles do not double-paint pixels, a bias of 1 is subtracted from edges that are ``top'' or ``left'' \cite{fgiesen}. 
\begin{gather}
A=Y_2 - Y_1 \label{eqn:a}\\
B=X_2 - X_1 \label{eqn:b}\\
C=BY_1 - AX_1 \label{eqn:c}
\end{gather}

This paragraph falls at the end of a page, so on the next page, I get a widowed line, followed by the equations:

enter image description here

And then it stretches out the inter-paragraph spacing on the previous page.

If I put a line break between the paragraph and the equation, it does let the paragraph end on the previous page. However, it then puts a huge blank space at the top of the next page where the equations are.

I have tried all sorts of tricks, like messing with the abovedisplayskip (no effect) and negative vspace (no effect until it got negative enough to pull the equations onto the previous page, overlapping the text).

I also did this, but to no effect:

\widowpenalty=10000
\clubpenalty=10000

Can anyone tell me how to get LaTeX to behave sensibly and let the paragraph end on the previous page and also have the equations line up at the top of the next page?

Thanks!

Best Answer

as i said in a comment, don't do it. if you are submitting this document to a well-edited math journal, it will be reversed.

however, if you must, this should work:

\documentclass{article}
\usepackage{amsmath}
\begin{document}
some text

\vfill
So that abutting triangles do not double-paint pixels, a bias of 1 is subtracted from edges that are ``top'' or ``left'' \cite{fgiesen}. 

\newpage
\noindent
\begin{minipage}{\textwidth}
\begin{gather}
A=Y_2 - Y_1 \label{eqn:d}\\
B=X_2 - X_1 \label{eqn:e}\\
C=BY_1 - AX_1 \label{eqn:f}
\end{gather}
\end{minipage}
\medskip
<resume text here>
\end{document}

within the minipage, the skip above the display will be suppressed. the skip below will also be suppressed, so you need to compensate for that. the actual value depends on the document class you're using, but \medskip seems to be a reasonable approximation.

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