图片标题问题

Question

有谁能猜出这个图说明有什么问题吗？

\caption{Graphical representation of the simple approximation proposed to determine the linewidth of a laser from its frequency noise PSD $S_{\delta\nu}(f)$, calculated from the surface \emph{A} of the slow modulation area. The shadowed areas on this schematized frequency noise spectrum represent the surface \emph{A} that encloses all spectral components for which $S_{\delta\nu}(f)$ exceeds the $\beta$\nobreakdash-separation line $S_{\delta\nu}(f) = \frac{8\ln2}{\pi ^2}f$ (dashed line).}

如果我不将其注释掉，我会收到以下错误消息：

inputenc: Keyboard character used is undefined(inputenc) in inputencoding `utf8'. ...) = \frac{8\ln2}{\pi ^2}f$ (dashed line).}

Incomplete \iffalse; all text was ignored after line 71

谢谢，理查德

Answer 1

当我将你的代码复制到我的编辑器中时，一个奇怪的字符出现在逗号后面

PSD $S_{\delta\nu}(f)$,

那个虚假字符必须被删除；还\nobreakdash需要被\protect编辑（如果您计划使用可选参数，那么这不是必需的\caption）。

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\begin{figure}
\caption{Graphical representation of the simple approximation proposed to determine the linewidth of a laser from its frequency noise PSD $S_{\delta\nu}(f)$, calculated from the surface \emph{A} of the slow modulation area. The shadowed areas on this schematized frequency noise spectrum represent the surface \emph{A} that encloses all spectral components for which $S_{\delta\nu}(f)$ exceeds the $\beta$\protect\nobreakdash-
separation line $S_{\delta\nu}(f) = \frac{8\ln2}{\pi ^2}f$ (dashed line).}
\end{figure}

\end{document}

笔记：

不幸的是，在原始问题和我的答案中格式化代码之后，虚假字符消失了，但它就在那里。