\nicefrac or \xfrac in \displaystyle

Question

How do I get \nicefrac or \xfrac work in \displaystyle, i.e., without reducing the font size?

Answer 1

As an alternative (since \nicefrac and \sfrac do not seem to be adjustable to representing digits in displaystyle)...

Adjusting my answer from Modifying fraction macro for in-line text and exponents, this will also set numerator and denominator as text if called in text mode, and as math in math mode.

\documentclass{article}
\usepackage{graphicx}

\newcommand{\altfrac}[2]{\ifmmode\def\tmp{$}\else\def\tmp{}\fi\mbox{%
    {\raisebox{.24\ht\strutbox}{\tmp#1\tmp}}%
    \kern-2.2pt\scalebox{1.6}[1.5]{/}\kern-1.8pt%
    {\tmp#2\tmp}%
    }}

\begin{document}
\parindent 0pt
This is \texttt{altfrac:}\qquad
\altfrac{12}{14} \altfrac{31415}{27182} \altfrac{abc}{def} \altfrac{Foo!}{Bar?}
\altfrac{\#\$\%+/<>=}{?\@[]\textbackslash\_|\{\}§†} 
\[\left(\frac{3x}{2y}\right)^{\altfrac{3}{2}}=\altfrac{\lambda}{2x}\]
\qquad And here is \altfrac{x}{y} versus $\altfrac{x}{y}$\\

\end{document}

WARNING: if used in inline mode, the size of the / will possibly cause the line spacing to temporarily adjust. While this can be eliminated by \smash'ing the \scalebox, that could result in glyph overlap.

Answer 2

Using \Large before is doing the trick :

\text{\Large$\sfrac{1}{10}$}

It's not a proper solution and more just a hack since it produces a warning (Font: Size substitution...) and it's has to be manually specified.

Here is a minimal example:

\documentclass[varwidth,margin=0.5cm]{standalone}
\usepackage{xfrac}

\begin{document}

\begin{itemize}
  \item $\frac{1}{10} =\sfrac{1}{10}$
  \item $\displaystyle\frac{1}{10} = \text{\Large$\sfrac{1}{10}$}$
\end{itemize}

\end{document}

And the corresponding output: