Math Operators and beamer

Question

I'm using xelatex and I'm having a very strange problem:

while

\documentclass{article}

\usepackage{xparse}
\usepackage{subfig}
\usepackage{amsmath}                                            
\usepackage{amsfonts}                                          
\usepackage{amssymb}                                            
\usepackage{amsthm}                                             
\usepackage{unicode-math} 
\begin{document}
  $$
  \sin(x)
  $$
\end{document}

is working perfectly:

\documentclass{beamer}

\usepackage{xparse}
\usepackage{subfig}
\usepackage{amsmath}                                            
\usepackage{amsfonts}                                          
\usepackage{amssymb}                                            
\usepackage{amsthm}                                             
\usepackage{unicode-math} 
\begin{document}
\begin{frame}
  $$
  \sin(x)
  $$
\end{frame}
\end{document}

doesn't dislay the "sin". It looks completely blank. How can I solve this problem?

Answer 1

Internally, beamer replaces certain fonts. Apparently the you don't have the replacement font in a place where XeLaTeX can find it, so it doesn't appear. To suppress this replacement, you can either load the beamer class with the professionalfont option, or add \usefonttheme{professionalfonts} to your preamble. (Note the difference!) See section 18.1 of the beamer documentation for details.

Also, see Why is [ … ] preferable to $$ … $$?

\documentclass[professionalfont]{beamer}
%\usefonttheme{professionalfonts}
\usepackage{xparse}
\usepackage{subfig}
\usepackage{amsmath}                                            
\usepackage{amsfonts}                                          
\usepackage{amssymb}                                            
\usepackage{amsthm}                                             
\usepackage{unicode-math} 
\begin{document}
\begin{frame}
  \[
  \sin(x)
  \]
\end{frame}
\end{document}