[XeTeX] Why is the fraction off the math axis in XeTeX?

Henri Menke henrimenke at gmail.com
Sun Dec 6 15:00:42 CET 2015


I asked this question on TeX.SX, but Enrico Gregorio suggested that this
is better suited for the XeTeX mailing list.  The question has
essentially the same content as this e-mail, but features some sample
images.  You may find it here:

https://tex.stackexchange.com/questions/281549/why-is-the-fraction-off-the-math-axis-in-xetex

Now to the problem:

The fraction in textstyle is off the math axis in XeTeX when I use a
Unicode math font. In LuaTeX, though, it aligns nicely with the math
axis. The follwing MWE should illustrate this. Also, in displaystyle
everything is fine.

\ifdefined\directlua
  \input luaotfload.sty
\fi
$-{1\over 2}$%
\font\ms="Latin Modern Math:script=math;+ssty=0" at 7pt
\scriptfont0=\ms
$-{1\over 2}$
\bye

How can I fix this? Does it suffice to adjust \fontdimen parameters?

This does not only happen in plain XeTeX, but also in LaTeX with the
unicode-math package. Unfortunately, I cannot show a side-by-side
comparison here, because unicode-math immediately changes the math font
to “Latin Modern Math”.

\documentclass{standalone}
\usepackage{unicode-math}
\begin{document}
$-\frac{1}{2}$
\end{document}

Kind regards, Henri


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