答案1
使用来自带虚线的分数或推理规则你可以定义\rcr{<num>}{<denom>}
:
\documentclass{article}
\usepackage{amsmath}
\newcommand{\dashdfrac}[2]{%
{\sbox0{$\genfrac{}{}{0pt}{0}{#1}{#2}$}%
\vphantom{\copy0}%
\ooalign{%
\hidewidth
$\vcenter{\moveright\nulldelimiterspace
\hbox to\wd0{%
\xleaders\hbox{\kern.5pt\vrule height 0.4pt width 1.5pt\kern.5pt}\hfill
\kern-1.5pt
}%
}$
\hidewidth\cr
\box0\cr}}%
}
\newcommand{\rcr}[2]{\biggl[\dashdfrac{#1}{#2}\biggr]_3}
\begin{document}
For relatively prime integers~$m$ and~$n$ define the \textbf{rational cubic residue symbol} as
\[
\rcr{m}{n} = \begin{cases}
1 & \text{$m$ is a cubic residue mod~$n$} \\
-1 & \text{$m$ is a cubic non-residue mod~$n$}
\end{cases}
\]
\end{document}
如果需要的话,可以\rcr
根据数学风格进行修改设置。
您还可以尝试
\newcommand{\rcr}[2]{\Bigl[\dashdfrac{#1}{#2}\Bigr]_3}