答案1
答案2
这应该是你想要的:
\documentclass{article}
\usepackage{amsmath}
\makeatletter
\DeclareRobustCommand{\crosscalS}{{\mathcal{S}\mathpalette\crosscal@S\relax}}
\newcommand{\crosscal@S}[2]{%
\makebox[0pt][r]{$\m@th#1\textnormal{-}\mkern-0.3mu$}%
}
\makeatother
\begin{document}
$\mathcal{S}\crosscalS\mathcal{S}$
$\mathcal{S}\mathcal{S}\mathcal{S}$ % check for the width
$X_{\mathcal{S}}X_{\crosscalS}$
\end{document}