16

I have an equation using fractions of fractions - much like

\frac{\frac{a}{b}}{\frac{c}{d}}

However, all of the fraction bars are the same width. I'd like to make the central bar wider than the others for improved readability. Is this possible? I've played around with shrinking the fond sizes of the numerator and denominator a bit, but that still doesn't improve readability.

2
  • Can you post a minimal working example (MWE)? The output of \documentclass{article}\begin{document}$\frac{\frac{a}{b}}{\frac{c}{d}}$\end{document} has different fraction bar lengths. Or didn't you mean the horizontal width but the line thickness? Commented Oct 25, 2012 at 14:00
  • 1
    When you say "width" do you mean "bar length" (horizontal width) or do you mean "bar thickness" (vertical width)?
    – chharvey
    Commented Mar 11, 2013 at 4:54

3 Answers 3

20

Some space can be added in the outer nominator/denominator, e.g.:

\documentclass{article}
\begin{document}
\[
  \frac{\,\frac{a}{b}\,}{\frac{c}{d}}
\]
\end{document}

Result

1
  • 3
    Oh yes it depends what was meant by "width" (English isn't very clear here) This changes the length (or width as you view it) of the line, whereas genfrac gives control over the thickness (which would be called the width of the line in other circumstances) Commented Oct 25, 2012 at 14:27
13

You can use \genfrac from the amsmath package.

       \genfrac{left-delim}{right-delim}{thickness}{mathstyle}{numerator}{denominator}
5
  • 1
    For orientation, the predefined values are about .4pt, .34pt and .24pt for text/display, script and scriptscript style respectively. Commented Oct 25, 2012 at 14:15
  • @Qrrbrbirlbel "about" or "exactly"? How can I derive the actual, precise values? Commented Mar 4, 2014 at 8:44
  • 1
    @LoverofStructure it is set by the fonts in use (fontdimen 8 of the font in \fam 3) see tex.stackexchange.com/questions/88991/… Commented Mar 4, 2014 at 9:42
  • @DavidCarlisle I'm wondering why the rule thickness isn't by default scaled depending on the mathstyle. Making it easy to have a mathstyle-dependent rule thickness for \genfrac would be good. Am I missing something, or is this an oversight on part of the amsmath folks? Commented Mar 5, 2014 at 3:24
  • 1
    @LoverofStructure the default thickness depends on the font so is dependent on the mathstyle normally (assuming a smaller font is used in scripts) if you want to change the defaults you can set different values for fontdimen8, otherwise the intention for \genfrac was probably one-off use so normal lengths are probably easier to use than mu units Commented Mar 5, 2014 at 8:26
4

Making the line thicker using the TeX primitive:

\def\oover{\abovewithdelims...8pt}
$$ {a\over b} \oover {c\over d} $$
\bye

enter image description here

where the first . is the left delimiter, second the right, and the last argument is a dimension for the fraction bar thickness.

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