[luatex] Wrong placement of \int\limits in Lua(La)TeX

[Simon May]

Are these known issues?
With such greatly differing output between TeX engines, how is one
expected to write portable TeX documents?


On 04.03.2015 15:26, Simon May wrote:
> (Apologies for breaking the thread – I hadn't subscribed to the list
> before.)
> 
> I agree that it's not trivial to decide where the limits should actually
> be, but I guess many things in typesetting are a matter of taste.
> However, I think anyone would agree that
> – Using the same TeX input, the output of Lua(La)TeX and Xe(La)TeX
>   should be (at least qualitatively) the same. If I decide that I want
>   or need to use a different engine for a document, I want to change
>   as little as possible (preferably nothing) in my document as a result.
>   If a change of engine produces significantly different output, that's
>   always a hint that there must be a bug somewhere.
> – "\limits" should mean that the limits of the operator are placed above
>   and below instead of to the sides. Whether one thinks that the
>   placement with unicode-math looks good or not, the limits are so far
>   to the side that it cannot really be said that they are placed above
>   and below.
> 
> Moreover, I really do think that the current placement with unicode-math
> looks just bad. The limits are floating somewhere to the upper
> right/upper left with barely any attachment to the operator they belong
> to. Originally, I thought that the placement and spacing demonstrated at
> https://tex.stackexchange.com/a/103925
> could universally agreed upon to be good-looking (and definitely better
> than the same document typeset with LuaLaTeX).
> 
> Now that I'm looking more closely at some tests, it seems that there is
> way too much space inserted after an integral sign with LuaLaTeX.
> Looking at the following TeX source:
> 
> \documentclass{scrartcl}
> \usepackage{unicode-math}
> \begin{document}
> \[
> 	A = \int f(x) \,\mathrm{d}x
> \]
> \end{document}
> 
> It seems like the amount of space between the integral sign and f(x) is
> almost doubled compared to the version without unicode-math. It actually
> looks really ugly. Perhaps this issue is related?
> 
> 
> Ulrike Fischer wrote:
>> Am Tue, 3 Mar 2015 20:03:33 +0100 schrieb Simon May:
>>
>>> Hello,
>>>
>>> with unicode-math and LuaLaTeX, the placement of the limits using
>>> \int\limits is incorrect. The limits are placed too far to the
>>> right. As
>>> discussed in the comments at
>>> https://tex.stackexchange.com/a/103925/51235
>>> this issue does not occur with XeTeX. There is also a bug at
>>> http://tracker.luatex.org/view.php?id=729
>>> that might refer to this same issue. Is this indeed a bug in LuaTeX
>>> and
>>> are there perhaps any workarounds?
>>> I'm using LuaTeX beta-0.79.1 (TeX Live 2014/Debian) (rev 4971).
>>>
>>> Below is a demonstration of this issue. Producing the document will
>>> show
>>> the incorrect placement of the limits. Removing the line
>>> "\usepackage{unicode-math}" will show the expected output.
>>>
>>>
>>> \documentclass{scrartcl}
>>> \usepackage{unicode-math}
>>> \begin{document}
>>> \[
>>> 	\int_a^b
>>> 	\int\limits_a^b
>>> \]
>>> \end{document}
>>
>> The placement is certainly different than with xelatex or without
>> unicode-math. But I do find it difficult to describe exactly where
>> the symbol should placed and I often don't like the placement in
>> pdflatex. It also depends a bit on the actual font. You can always
>> move the subscripts a bit if you want:
>>
>> \documentclass{scrartcl}
>> \usepackage{unicode-math}
>> %\setmathfont{Cambria Math}
>> \begin{document}
>> \[
>> 	\int_a^b
>> 	\int\limits_{\!\!\!\!a}^{b}
>>     \int\limits_{a}^{b}
>>     \int\limits_{a}^{b=5}
>>     \int\limits_{a=1}^{b}
>>     \int\limits_{a=1}^{b=5}
>> \]
>> \end{document}
>>
>>
>>> Out of interest: Using unicode-math (even without limits) does not
>>> produce the same output in the example as the same document without
>>> unicode-math. The the size of the integral sign and the spacing of
>>> the limits changes slightly. Is this intended/expected?
>>
>> You are using different fonts. So differences are always possible.
>>
>>
>> --
>> Ulrike Fischer
>> http://www.troubleshooting-tex.de/
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