[XeTeX] Accessing mathmatics symbols

[R (Chandra) Chandrasekhar]

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

Hendrik Fuß wrote:

> Does xdvipdfmx produce any error messages if you remove the -q flag?

Yes, there is a warning message and also a PDF output file that does not have 
the missing mathematics symbols:

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

gives

** WARNING ** Glyph "(null)" missing in font "LMMathSymbols10-Italic".

> The square root sign is not taken from the mathrm font, but from
> LaTeX's legacy math fonts (ie lmodern). My guess is you might have to
> run updmap to update the font database for xdvipdfmx.

You may have pinpointed the cause here.  I did

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 whet else must be done to get around this problem.

Thank you.

Chandra