[XeTeX] Use Type 1 Math Fonts with fontspec

[Jjgod Jiang]

Hi,

I'm wondering why this sample:

\documentclass[11pt]{article}
\usepackage[varg]{txfonts}
\usepackage{fontspec}

\setmainfont{Times Roman}

\begin{document}
\huge $\sin x + \alpha \frac{1}{2} \sum^{100}_{i=a}$
\end{document}

can not change font of the digits while this do:

\documentclass[11pt]{article}
\usepackage[varg]{txfonts}

\begin{document}
\huge $\sin x + \alpha \frac{1}{2} \sum^{100}_{i=a}$
\end{document}

Both of them are typesetted with
xelatex --output-driver="xdvipdfmx -q -E".

- jjgod.