Typesetting LaTeX fraction terms to be larger in an equation

Question

I have the following formula in LaTeX, based on Fisher's Exact Test. (NOTE: requires the use of the amsmath package for \binom.)

\begin{equation}
    P(i,j) = \sum_{x=|N(V_i) \cap V_j|}^{\min\{|V_j|, |N(V_i)|}
    \frac{ \binom{|V_j|}{x} \binom{|V - V_j|}{|N(V_i)| - x}}
    {\binom{|V|}{|N(V_i)|}}
\end{equation}

This renders the fraction portion with very small, difficult to read text:

$equation with small text in fraction$

I would like my text more readable, as in the following example:

$equation with readable text in fraction$
_{(source: plosone.org)}

What trickery can I use to get LaTeX to render my equation similarly?

The second example is from Word's Equation Editor, isn't it? — Charles Stewart, Apr 18 '10 at 08:17
@Charles I'm not sure how it was generated, but it appears in the following article in PLoS One: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0005313 — gotgenes, Apr 19 '10 at 01:51

score 16 · Accepted Answer · edited Feb 08 '17 at 14:24

This may be what you're looking for:

\begin{equation}
    P(i,j) = \sum_{x=|N(V_i) \cap V_j|}^{\min\{|V_j|, |N(V_i)|} 
    \frac{\displaystyle \binom{|V_j|}{x} \binom{|V - V_j|}{|N(V_i)| - x}}
    {\displaystyle \binom{|V|}{|N(V_i)|}}   
\end{equation}

Formatted equation

Thought it might be good to add a reference:

A Guide to LaTeX2e, Kopka & Daly, 1995
Section 5.5 Fine-Tuning Mathematics
5.5.2 Selecting font size in formulas

In my edition, it's on pp 141-142, but this is out of stock on Amazon. The nearest Internet pointer I can find just now is here

score 11 · Answer 2 · edited Oct 22 '21 at 15:13

11

For fraction you can also use continued fraction \cfrac in combination with \left and \right.

Take a look here.

edited Oct 22 '21 at 15:13

faken

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answered May 31 '13 at 16:06

Thijs

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I would consider `cfrac` to be the most correct answer. – sircolinton Apr 16 '15 at 15:54
The link is broken. – Paul Wintz Aug 14 '20 at 11:21
1

@PaulWintz: fixed. – faken Oct 22 '21 at 15:13

score 6 · Answer 3 · edited Feb 08 '17 at 14:24

6

Here's one idea.

In Preamble:

\def\mathLarge#1{\mbox{\LARGE $#1$}}

Then update your equation to:

\begin{equation}
    P(i,j) = \sum_{x=|N(V_i) \cap V_j|}^{\min\{|V_j|, |N(V_i)|}  
    \mathLarge{
        \frac{ \binom{|V_j|}{x} \binom{|V - V_j|}{|N(V_i)| - x}}
        {\binom{|V|}{|N(V_i)|}}
    }
\end{equation}

Results in:

alt text

edited Feb 08 '17 at 14:24

Community

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answered Apr 18 '10 at 15:49

Geoff

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Very nice alternative, with the added bonus of having greater control over the size of the text in the fraction. – gotgenes Apr 19 '10 at 01:54

score 2 · Answer 4 · answered Feb 01 '15 at 14:04

The following lines define three fraction commands with sizes intermediate between \displaystyle and \textstyle, in order of decreasing size:

\newcommand{\sdfrac}[2]{\mbox{\small$\displaystyle\frac{#1}{#2}$}}
\newcommand{\fdfrac}[2]{\mbox{\footnotesize$\displaystyle\frac{#1}{#2}$}}
\newcommand{\ltfrac}[2]{\mbox{\large$\frac{#1}{#2}$}}

See this page if further explanation is needed.

Typesetting LaTeX fraction terms to be larger in an equation

4 Answers4

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