# [XeTeX] [Dev-luatex] Unicode-Math in LuaLaTeX and XeLaTeX

Mathias Schickel msch at fa.uni-tuebingen.de
Wed Dec 12 14:14:30 CET 2018


> Am 12.12.2018 um 12:06 schrieb Ulrike Fischer <luatex at nililand.de>:
>
>> The first issue is the usage of the staircase kerning boxes of
>> opentype math fonts. They are obviously not applied in expressions
>> like $f_j$ using LuaLaTeX. The index is rendered too far away from
>> the glyph. If we use XeLaTeX we get the correct output.
>
> It works okay with luatex 1.09 (miktex or dev-TeXLive), but fails in a
> current texlive 2018.

Okay, that is good news. How can I receive the required luatex file? I am on a Mac and TeXLive is the standard distribution there. Till now I did not know anything of dev-TeXLive and how to install it. Would it be possible to simply send the current luatex 1.09 file to me so that I can replace the file in the standard distribution? Or would that require more complicated actions?

>
>
>> The second issue is present in both LuaLaTeX and XeLaTeX. If we
>> have an index together with an exponent like j the index is rendered
>> too high – in fact it is risen compared to the expression that uses
>> an index only. A typical example is $f_n^j$.
>
> The sup/sub pair is higher placed than with context. You could move it
> down (at least with luatex) with

It is obvious that the higher placement in LuaLaTeX and XeLaTeX cannot be intended and thus should be considered as a bug.

Have a look at the attached file. This time I have chosen Latin Modern Math because it is a little bit more significant there. Notice that $f_n$ and even $f_n^m$ have the correct and standard placement while $f_n^j$ shows the higher placement of the index $n$. There is no reason why the $n$ should be placed higher if the exponent is $j$ instead of $m$. On the contrary it would make much more sense if the $n$ would be placed lower(!) and not higher if the exponent goes below the baseline and has a descender height > 0.

>
> \documentclass{article}
> \usepackage{unicode-math}
> \setmathfont{Cambria Math}
> \begin{document}
> $f_n^j$
>
> \Umathsupsubbottommax\textstyle =2pt
> $f_n^j$
> \end{document}
>
> unicode-math could probably offer some option to set this.

Maybe this could be a workaround as long as the bug persists. Has anyone an idea how this could be done as standard procedure using unicode-math?

>
>
> --
> Mit freundlichen Grüßen
> Ulrike Fischer
> mailto:luatex at nililand.de
>

Kind regards,
Mathias Schickel

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