# [Tex/LaTex] Smaller fractions in displayed formulae

displaystylefractions

How do you make script-sized fractions in display mode?

In certain cases, I find that \frac-based fractions are too large for my tastes in displayed formulae. For example, I feel that the fractions here stand out way too much compared to the exponents: I can hack a workaround by writing things like \frac{_1}{^{24}}, but that seems like too much trouble. The result, however, does look more like what I want: Alternatively, I can force text styling by writing things like {\textstyle\frac{1}{24}}. This feels cleaner to me, but I'm not sure it looks as readable as the earlier hacked version because the fractions are tighter vertically (great for text mode but a bit much for display mode). What would you do?

\documentclass{minimal}
\begin{document}

$\cos x = \sum_{n=0}^\infty \frac{(-1)^n}{(2n)!} x^{2n} = 1 - \frac{1}{2}x^2 + \frac{1}{24}x^4 - \frac{1}{720}x^6 + \cdots$

$\cos x = \sum_{n=0}^\infty \frac{(-1)^n}{(2n)!} x^{2n} = 1 - \frac{_1}{^2}x^2 + \frac{_1}{^{24}}x^4 - \frac{_1}{^{720}}x^6 + \cdots$

$\cos x = \sum_{n=0}^\infty \frac{(-1)^n}{(2n)!} x^{2n} = 1 - {\textstyle\frac{1}{2}}x^2 + {\textstyle\frac{1}{24}}x^4 - {\textstyle\frac{1}{720}}x^6 + \cdots$

\end{document}


Use amsmath's \tfrac or \dfrac constructs to forcibly write a fraction in text or display style. In amsmath.sty, these macros are defined via \genfrac

\newcommand{\dfrac}{\genfrac{}{}{}0}
\newcommand{\tfrac}{\genfrac{}{}{}1}


with the token 0/1 setting the math style to \displaystyle/\textstyle (2 is for \scriptstyle; 3 is for \scriptscriptstyle, for what it's worth).

Here's a MWE: \documentclass{article}
\usepackage{amsmath}% http://ctan.org/pkg/amsmath
\begin{document}
\begin{align*}
\cos x &= \sum_{n=0}^\infty \frac{(-1)^n}{(2n)!} x^{2n}
= 1 - \frac{1}{2}x^2 + \frac{1}{24}x^4 - \frac{1}{720}x^6 + \dotsb\\[2\baselineskip]
\cos x &= \sum_{n=0}^\infty \dfrac{(-1)^n}{(2n)!} x^{2n}
= 1 - \dfrac{1}{2}x^2 + \dfrac{1}{24}x^4 - \dfrac{1}{720}x^6 + \dotsb \\[2\baselineskip]
\cos x &= \sum_{n=0}^\infty \tfrac{(-1)^n}{(2n)!} x^{2n}
= 1 - \tfrac{1}{2}x^2 + \tfrac{1}{24}x^4 - \tfrac{1}{720}x^6 + \dotsb
\end{align*}
\end{document}​