Remove white line after \item in enumerate and before display math

Question

The goal is to remove the white line after the 1. in the second enumerate in the picture, so it will look like the first enumerate.

I don't like the first enumerate because it uses inline math, needs the white line in the code to make a new paragraph, and uses \displaystyle which I think is not the way to go: it feels like a 'hack'. Maybe I am mistaken, in that case say so, but I think there must be a good solution.

MWE:

\documentclass[english]{exam}
\usepackage[fleqn]{amsmath}

\begin{document}

    \begin{enumerate}  %result looks fine, but code ugly
        \item 
        $\displaystyle \pi$ 

        $\displaystyle 2\pi$
    \end{enumerate}

    \begin{enumerate} %code looks fine, but result ugly
        \item 
        \[\pi\]
        \[2\pi\]
    \end{enumerate}

\end{document}

Welcome, you are using a displayed math environment. Their purpose is to present their content on an extra line. — Johannes_B, May 16 '16 at 14:45
@Johannes_B But even in an enumerate? So I should use the \displaystyle? — PHPirate, May 16 '16 at 14:51
I think this is a classical XY-question. So you want math in an enumerate? Or do you want to enumerate math? If you ake that clear, an experienced user can help you find a solution. — Johannes_B, May 16 '16 at 14:52
@Johannes_B I want math in an enumerate, as said like in the first enumerate in the picture. But I want to avoid using \displaystyle because I don't like typing that every time in an inline math environment. — PHPirate, May 16 '16 at 14:55

Bernard · Answer 1 · 2016-05-16T15:38:23.037

5

Simply try this:

\documentclass{article}
\usepackage[fleqn]{amsmath}
\newcommand\mathitem{\item\leavevmode\vspace*{-\dimexpr\baselineskip+\abovedisplayskip\relax}}

\begin{document}

    \begin{enumerate} %
        \mathitem \begin{gather*}
          \pi\\2\pi
        \end{gather*}

    \end{enumerate}

\end{document}

edited May 16 '16 at 15:38

answered May 16 '16 at 15:20

Bernard

271,350

Good one, a big advantage is that you don't need to install an extra package locally, and I like the use of gather. – PHPirate May 16 '16 at 15:26
@PHPirate Don't forget to upvote a question you like especially if you have accepted ;-) – Tarass May 16 '16 at 16:01
@Tarass That is exactly what I wanted to, except that SE complains I don't have enough reputation yet :D – PHPirate May 16 '16 at 16:11

Steven B. Segletes · Accepted Answer · 2016-05-16T15:09:31.693

One problem is that \[...\] environments always add extra vertical space and try to center their contents (the fleqn might help to avoid that). Using a \tesxtstyle approach with $ delimiters is the typical approach for what you seem to want. But if \item is just a bunch of left-aligned stacked math, this might be more streamlined.

Maybe one of (or some combination of) the following three stack approaches would work for you (no fleqn required).

\documentclass[english]{exam}
\usepackage{tabstackengine}
\stackMath
\makeatletter\renewcommand\TAB@delim[1]{\displaystyle#1}\makeatother
\setstackEOL{\cr}% ROW DELIMITER FOR STACKS
\renewcommand\stackalignment{l}% LEFT ALIGNMENT OF STACKS
\setstackgap{S}{8pt}% INTER-ROW PADDING OF SHORT STACKS
\begin{document}
    \begin{enumerate}  %result looks fine, but code ugly
        \item 
%       FOR SIMPLE REGULAR-HEIGHT STACKS
        \Longunderstack{\pi\cr 2\pi}
        \item 
%       FOR IRREGULAR HEIGHT STACKS IN \textstyle
        \Shortunderstack{\pi\cr \frac{2\pi}{x}\cr \frac{\pi^3}{\pi_x}}
        \item 
%       FOR IRREGULAR HEIGHT STACKS IN \displaystyle
        \tabbedShortunderstack{\pi\cr \frac{2\pi}{x}\cr \frac{\pi^3}{\pi_x}}
    \end{enumerate}
\end{document}

If typing \tabbedShortunderstack was too much work each time, one could, for example, \let\Estack\tabbedShortunderstack in the preamble.

Looks fine, but my tex installation can't find the package file, so hang on a minute. — PHPirate, May 16 '16 at 15:00
@PHPirate Try https://www.ctan.org/pkg/tabstackengine and https://www.ctan.org/pkg/stackengine. — Steven B. Segletes, May 16 '16 at 15:02
Thanks, that worked! Indeed, for individual cases I'll just use the \textstyle approach as you say, but the stacking is a good bonus for when you have a lot of it. — PHPirate, May 16 '16 at 15:08

score 1 · Answer 3 · answered Jul 13 '19 at 03:43

1

One more (simple) solution:

\documentclass{article}
\usepackage{amsmath}

\begin{document}
\begin{enumerate} 
  \item $\begin{aligned}[t]
          x & = 0   \\
          y & = \frac{1}{2}
        \end{aligned}$
\end{enumerate}
\end{document}

answered Jul 13 '19 at 03:43

Zarko

296,517

score 0 · Answer 4 · answered Jul 13 '19 at 06:30

With the extension witharrows correctly parameted, you have directly the result. Of course, the main purpose of the extension witharrows is to add arrows. That's, why, in the following example, I have added an arrow.

\documentclass[english]{exam}
\usepackage[fleqn]{amsmath}
\usepackage{witharrows}
\WithArrowsOptions{fleqn,displaystyle,mathindent = 0pt,notag}
\begin{document}
\begin{enumerate}
\item
\begin{DispWithArrows}[format=c]
\frac{2\pi}{3} \Arrow[tikz=-]{which one?}\\
\frac{5\pi}{4}
\end{DispWithArrows}
\end{enumerate}
\end{document}

Remove white line after \item in enumerate and before display math

4 Answers4

Linked