Vertical spacing between fractions in matrix environment

Question

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How can I increase the line spacing in a matrix?
Using display style fraction in a matrix environment
How to add extra spaces between rows in tabular environment?

When a fraction is used in a matrix environment, not enough vertical space is put between the rows. Wikibooks recommends using the \em command, but this seems like an inelegant solution. Is there an elegant solution?

It is always best to compose a MWE that illustrates the problem including the \documentclass so that those trying to help don't have to recreate it. — Peter Grill, Nov 02 '11 at 23:30
@PeterGrill I would have, but this seems like such an obvious scenario that an MWE isn't necessary and actually clutters the question. Am I wrong? — Quinn Culver, Nov 02 '11 at 23:37
Possible duplicates: http://tex.stackexchange.com/questions/26690/how-to-add-extra-spaces-between-rows-in-tabular-environment, http://tex.stackexchange.com/questions/31672/column-padding-in-tables — Werner, Nov 02 '11 at 23:39
@Quinn: MWEs are always welcome and definitely encouraged, since subjective views may interpret questions differently. — Werner, Nov 02 '11 at 23:41
Yeah I realize it is not that hard, but anyone who wants to provide a solution will have to create it to test it and if you provide one to start there is less chance of misinterpretations. — Peter Grill, Nov 03 '11 at 00:09

score 33 · Answer 1 · edited Jun 11 '17 at 20:08

33

One approach is to add extra space between specific lines, with an optional argument to \\:

\left[\begin{matrix}
    \frac{1}{2} & \frac{3}{2} \\
    \frac{5}{2} & \frac{7}{2}
\end{matrix}\right]

produces

While

\left[\begin{matrix}
    \frac{1}{2} & \frac{3}{2} \\[6pt]
    \frac{5}{2} & \frac{7}{2}
\end{matrix}\right]

produces

edited Jun 11 '17 at 20:08

barbara beeton

88,848

answered Nov 02 '11 at 23:50

jtbandes

4,262

4

Note that the OP wanted to avoid this approach – cmhughes Nov 03 '11 at 02:12
@cmhughes: Hm, I didn't see that in the post. Where was it stated? – jtbandes Nov 03 '11 at 04:26
Wikibooks recommends using the \em command, but this seems like an inelegant solution. No big deal though, it gets the job done :) – cmhughes Nov 03 '11 at 04:48
OK, I did see that, so I guess my question is... is \em equivalent to \? – jtbandes Nov 03 '11 at 04:54
1

The Wikibooks link recommends using \\[0.3em] and you used \\[6pt]. The similarity (in my mind) is that both are manual approaches. – cmhughes Nov 03 '11 at 05:14
Ah... I thought \em was a macro rather than a unit! – jtbandes Nov 03 '11 at 05:56
@cmhughes -- em is a horizontal measure; better would be ex since it is a vertical measure. wikibooks should be corrected. – barbara beeton Nov 03 '11 at 16:42
@jtbandes -- \em is a macro; an old one meaning "emphasize" (usually resulting in italic). em is the em width of the current font, typically 10pt for a 10pt font. – barbara beeton Nov 03 '11 at 16:44
This is great, when you don't want to change it for all matrices, because not all matrices will contain fractions, sums, products or similar big things. – Zelphir Kaltstahl Sep 04 '16 at 10:43

score 19 · Answer 2 · edited Jun 11 '17 at 20:09

19

If you use an array environment then you can use the command

\renewcommand{\arraystretch}{2.5}

and tweak it to whatever you would like. I have loaded the amsmath package to use \dfrac

screenshot

\documentclass{article}
\usepackage{amsmath}

\begin{document}

Default:
\[
    \left[
         \begin{array}{ccc}
         \dfrac{5}{6} & \dfrac{1}{6} & 0           \\
         \dfrac{5}{6} & 0           & \dfrac{1}{6} \\
         0           & \dfrac{5}{6} & \dfrac{1}{6}
        \end{array}
    \right]
\]
\renewcommand{\arraystretch}{2.5}
Stretched:
\[
    \left[
         \begin{array}{ccc}
         \dfrac{5}{6} & \dfrac{1}{6} & 0           \\
         \dfrac{5}{6} & 0           & \dfrac{1}{6} \\
         0           & \dfrac{5}{6} & \dfrac{1}{6}
        \end{array}
    \right]
\]
\end{document}

edited Jun 11 '17 at 20:09

barbara beeton

88,848

answered Nov 02 '11 at 23:35

cmhughes

100,947

But isn't this bad because it used array where matrix is more appropriate? – Quinn Culver Nov 04 '11 at 15:37
@Quinn: that's up to you! If you'd prefer to use matrix then have a look at the links that people have posted as comments – cmhughes Nov 04 '11 at 15:46
This works for more than two lines as it centers the middle lines. – Yvon Mar 17 '21 at 20:27

score 1 · Answer 3 · answered Nov 03 '11 at 07:42

In plain-tex format at least, \matrix calls \normalbaselines, which resets the (base)lineskip(limit)'s to normal(base)lineskip(limit)'s. Plain also has a macro called \openup<dimen> which increases the (base)lineskip(limit)'s by given <dimen>.

So it would seem logical to define a macro \openupnormal, which would do the same as \openup, only for normal(base)lineskip(limit)'s:

\catcode`@=11
\def\openupnormal{\afterassignment\@penupnormal\dimen@=}
\def\@penupnormal{\advance\normallineskip\dimen@
  \advance\normalbaselineskip\dimen@
  \advance\normallineskiplimit\dimen@}
\catcode`@=12

so that one could do:

$$
  \left[
    \openupnormal1\jot\matrix{ % inside this group, increase the
                               % normal(base)lineskip(limit)'s by 1 jot
      {5\over6} & {1\over6} & 0 \cr
      {5\over6} & 0 & {1\over6} \cr
      0 & {5\over6} & {1\over6} \cr
    } % the group ends here, and so does the effect of \openupnormal
  \right]
  \quad
  \left[
    \matrix{
      {5\over6} & {1\over6} & 0 \cr
      {5\over6} & 0 & {1\over6} \cr
      0 & {5\over6} & {1\over6} \cr
    }
  \right]
$$
\bye

enter image description here

(Note that there is no \displaystyle in effect in the above fractions, unlike in \dfrac)

I use LaTeX, not plain-TeX. Will this still work? Is there an analogous solution for LaTeX? — Quinn Culver, Nov 04 '11 at 15:36
I tried it with LaTeX and no errors. But I suppose you'd write things differently with LaTeX (\makeatletter/\makeatother instead of \catcode's, \frac/\dfrac instead of {x\over y}, \\[/\\] instead of $$ etc. — morbusg, Nov 04 '11 at 15:48

Vertical spacing between fractions in matrix environment

3 Answers3