Accessing mathmatics symbols within XeTeX

["R (Chandra) Chandrasekhar" <chandra@ee.uwa.edu.au>]

Dear Folks,

I posted this email to the XeTeX mailing list at:

http://tug.org/pipermail/xetex/2007-June/006733.html

reproduced below for convenience.

*************
I am trying out XeTeX (XeTeX 3.141592-0.996 (Web2C 7.5.6)) installed newly from
TeXLive 2007 source packages for K/Ubuntu Gutsy backported to Feisty.

I have installed the Latin Modern OTF fonts in addition to the lmodern package.

I am having problems getting maths symbols to appear in the output PDF files.

A minimal example is given below:
-------------
\documentclass[a4paper,10pt]{article}
%
\usepackage{fontspec}
\usepackage{xunicode}
\usepackage{xltxtra}
\usepackage[EU1]{fontenc}% Unsure if this is correct
\usepackage{textcomp}
%
\setmainfont{FreeSerif}
\setmathrm{LMRoman10 Regular} % is this really needed?
\defaultfontfeatures{Mapping=tex-text,Scale=MatchLowercase}
%
\begin{document}
$\sqrt{2}$ is an irrational number.
\[
\sum_{i = 1}^{10}i = 55
\]
%
\end{document}
-------------

When I process this file with

xelatex -output-driver="xdvipdfmx -q -E" <filename>

I do not get a square root or capital sigma summation sign.
*************

A reply at

http://tug.org/pipermail/xetex/2007-June/006736.html

suggested that the font database for xdvipdfmx might not have been updated.

I have replied at

http://tug.org/pipermail/xetex/2007-June/006737.html

with a summary below:

I tried

sudo updmap-sys

Among the output was:
--------
updmap: Generating output for ps2pk...
updmap: Generating output for dvips...
updmap: Generating output for pdftex...
updmap: Generating output for dvipdfm...
updmap: All output generated!
--------

But xdvipdfmx is missing. I wonder whether this is an omission in the
Debian/Ubuntu package installation scripts or something else. I remember
installing a separate xdvipdfmx package from the SIL website but the not with
the new TeXLive 2007 distribution.

Also, adding

\usepackage{lmodern}

in the preamble did not fix the problem.

I would appreciate knowing what else must be done to get around this problem.

Thank you.

Chandra