![longtable、\multicolumn 和 \boldmath](https://linux22.com/image/344518/longtable%E3%80%81%5Cmulticolumn%20%E5%92%8C%20%5Cboldmath.png)
以下代码可以编译
\documentclass{article}
\usepackage{longtable}
\begin{document}
\begin{longtable}{c}
\noalign{\bfseries $r$ test}
\multicolumn{1}{c}{Line 1}
\end{longtable}
\end{document}
但这个没有
\documentclass{article}
\usepackage{longtable}
\begin{document}
\begin{longtable}{c}
\noalign{\bfseries\boldmath $r$ test}
\multicolumn{1}{c}{Line 1}
\end{longtable}
\end{document}
我收到错误消息misplaced \omit
。我必须将括号加倍:
\noalign{{\bfseries\boldmath $r$ test}}
知道原因吗?