# How do I suppress the whitespace above an equation block at the page top?

How do I suppress the whitespace above the equation block at the page top ? It is added to the top margin, and I don't want that to happen. I know that \abovedisplayshortskip controls this for the whole document, but how can I change this for this particular equation block and NOT for any others ? Negative vspace doesn't work.

\documentclass[pdftex,12pt,a4paper,english,dutch,leqno]{article}
\usepackage[top=1cm,right=1cm,bottom=1cm,left=1.5cm,noheadfoot]{geometry}
\usepackage{babel}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{empheq}

\begin{document}

\abovedisplayskip=6pt
\abovedisplayshortskip=3pt % This should NOT be changed
\belowdisplayskip=6pt
\belowdisplayshortskip=3pt

\begin{equation*}
\left.\begin{array}{r}
a_{31}'=a_{11}\cdot a_{31}-a_{31}\cdot a_{11}=0\\
a_{32}'=a_{11}\cdot a_{32}-a_{31}\cdot a_{12}\\
a_{33}'=a_{11}\cdot a_{33}-a_{31}\cdot a_{13}\\
a_{34}'=a_{11}\cdot a_{34}-a_{31}\cdot a_{14}\\
b_{3}'=a_{11}\cdot b_{3}-a_{31}\cdot b_{1}
\end{array}\!\!\right\}
\Longrightarrow\;
\begin{matrix*}[l]
\text{Pseudo-code :}\\
a_{11}\cdot b_{3}-a_{31}\cdot b_{1}\mapsto b_{3}\text{.}\\
\forall\;i\in\{4,3,2,1\} : a_{11}\cdot a_{3i}-a_{31}\cdot a_{1i}\mapsto a_{3i}\text{.} \end{matrix*}
\end{equation*}

\end{document}

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If the problem is that you need to move the display to the next page, add \pagebreak at the end of the text that precedes the display. The space will automatically disappear. – egreg Nov 6 '12 at 15:49
It is strongly discouraged to start a page with displayed formulas. – Hendrik Vogt Nov 6 '12 at 16:38

## 2 Answers

It is not a skip that you have above the equation but a one line paragraph consisting of an indentation box and parfillskip glue. TeX display math environments do not generally react well to starting a paragraph they are designed to work mid-paragraph. If you need to do this you need to suppress the paragraph start with

\noindent
\begin{equation*}


and you will see the equation move up the page.

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If you will use equation with {split} inside, \noindent will not help you, because equation will appear a little higher then top of page. Add showframe option to geometry package and put this code in your document:

\clearpage
\noindent
$\begin{split} \left(a^{B^{B^{B}}}\right) \\ bb \end{split}$


Here is a solution which helped me How to place amsmath equations at top of page ignoring \topskip?

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