changing vertical spacing before and after math display mode

Question

I am writing a double space document, but I do not want excessive spacing between math display environments. For things like code listings I can use etoolbox and say \AtBeginEnvironment{minted}{\setstretch{1}} etc, is there a way to modify the stretch before / after math display?

\documentclass{article}
\usepackage{lipsum}
\usepackage[margin=0.5in]{geometry}

\usepackage{setspace}
\setstretch{2}

% kind of does the right thing, but only at the bottom...
% \everydisplay{\vspace*{-1em}}

\usepackage{amsmath}

% i think this is only for align?
% \belowdisplayskip=0pt

% this also doesn't work, just for array?
% \setlength{\jot}{-1ex}

\usepackage{etoolbox}
% is math / amsmath an environment?
\AtBeginEnvironment{math}{\setstretch{1}}
\AfterEndEnvironment{math}{\setstretch{2}}

\begin{document}
    \lipsum[1]

    % desired effect without manual every time
    % \setstretch{1}
    $$
        ax + by + cz + d = 0
    $$
    % not really even working
    % \setstretch{2}\vspace*{-2em}

    \lipsum[2]
\end{document}

I want to do this globally, getting rid of the spacing denoted by the red rectangles

I feel like this has to be a duplicate, but I can't get anything I find to work :/ If it matters, the above code was pdftex but I'm writing with xetex. I don't think that makes a difference in this question, but it may.

Answer 1

There are two errors in your input:

• the usage of $$ (see Why is \[ ... \] preferable to $$ ... $$?),
• blank lines before the display.

You can use the nodisplayskipstretch option to setspace, which will reduce the spacing to acceptable ones.

\documentclass{article}
\usepackage[margin=0.5in]{geometry}
\usepackage{amsmath}
\usepackage[nodisplayskipstretch]{setspace}

\usepackage{lipsum}

\setstretch{2}

\begin{document}

\lipsum*[1]% no \par or blank line before a math display
\[% not $$
ax + by + cz + d = 0
\]% and no blank line after a math display, generally.
\lipsum[2]

\end{document}

For comparison, here is the output without the option

and also what you get with blank lines and $$

I also add the output with \doublespacing (it's commonly believed that double spacing means \setstretch{2}, which is incorrect).

Answer 2

The solution for this is to modify the next lengths:

\abovedisplayskip, \belowdisplayskip, \abovedisplayshortskip and \belowdisplayshortskip

Example that shows what happens:

\documentclass{article}

\usepackage{lipsum}

\begin{document}

{\Large Normal}

test text that has to be long enought to go over the formula
\[f(x)=3\]
test continue text that will be long enought too

test text that is short
\begin{equation}
  x=f(y)
\end{equation}
test continue text that will be long enought too

{\Large All Zero}

\setlength{\abovedisplayskip}{0pt}
\setlength{\belowdisplayskip}{0pt}
\setlength{\abovedisplayshortskip}{0pt}
\setlength{\belowdisplayshortskip}{0pt}


test text that has to be long enought to go over the formula
\[f(x)=3\]
test continue text that will be long enought too

test text that is short
\begin{equation}
  x=f(y)
\end{equation}
test continue text that will be long enought too

{\Large normal 10pt short 5pt}

\setlength{\abovedisplayskip}{10pt}
\setlength{\belowdisplayskip}{10pt}
\setlength{\abovedisplayshortskip}{5pt}
\setlength{\belowdisplayshortskip}{5pt}


test text that has to be long enought to go over the formula
\[f(x)=3\]
test continue text that will be long enought too


\lipsum[3]

test text that is short
\begin{equation}
  x=f(y)
\end{equation}
test continue text that will be long enought too

\end{document}

Edit after OP's (first) comment:

You can add this code to your preamble. Every font change, will include a \selectfont command (hidden or not) and so, it will survive after font changes too (size and shape I think).

\def\mycommand{\setlength{\abovedisplayskip}{0pt}%
\setlength{\belowdisplayskip}{0pt}%
\setlength{\abovedisplayshortskip}{0pt}%
\setlength{\belowdisplayshortskip}{0pt}}

\let\oldselectfont\selectfont
\def\selectfont{\oldselectfont\mycommand}

\mycommand

Source: http://latex.org/forum/viewtopic.php?t=4993 from Stefan Kottwitz.

Output:

PS: The short skip used more in cases that big is not necessary to separate clean enough the math from the text. (amsmath package uses more options for these skips.. for more about this here: abovedisplayskip vs abovedisplayshortskip)

PS2: See @dalief's comment