[Tex/LaTex] Different space between \align and \equation

alignequationsspacing

Why produce the align and the equation environment different space between the text. And what can I do, that it have the same?

\documentclass{article}
\usepackage{amsmath}

\begin{document}

Long Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text

\begin{align}
 1+1=2
\end{align}

Again a long text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text

\begin{equation}
 1+1=2
\end{equation}

Another Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text

\end{document}

Best Answer

The calculations are a bit different so they are not always same but the reason why the spacing is so bad in your example is that you should never have a blank line before a display math. The visible space is not (to TeX) a vertical space but a spurious extra paragraph with just an indentation box and parfillskip glue and no text making a blank line in addition to the intended space.

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

Long Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text
\begin{align}
 1+1=2
\end{align}

Again a long text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text
\begin{equation}
 1+1=2
\end{equation}

Another Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text, Text

\end{document}

enter image description here

equation uses two possible spaces \abovedisplayskip and \abovediplayshortskip depending on whether there is an overlap between the last row of the previous para and the equation. As far as I recall align doesn't do that (as essentially it's always full width internally even if visually smaller) you can stop equation closing up small cases with 

\begin{document}
\abovedisplayshortskip=\abovedisplayskip

Or perhaps better if you want all displays to use a consistent AMS style, use gather instead of equation

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