Hi all,

I encountered some strange behaviour regarding the subscript and superscripts in LuaLaTeX compared to pdfLaTeX. Consider the following small example:

%\RequirePackage{luatex85}
\documentclass{scrartcl}
%\usepackage{subdepth}
%\usepackage{unicode-math}

\begin{document}
\[a_ia_i^+a^+a_i^\dagger\]
\[M_n M_n^\dagger M_n^+\]
\end{document}

Compilation with pdfLaTeX results in shifted positions for the sub and super scripts according to the TeXbook. The package subdepth equalizes them, which in this case looks nicer. With LuaLaTeX, the subdepth package does not work, and has no effect on the positioning whatsoever. David suggested to ask for a reason for this behaviour on the luatex-list. Making things more complicated: If I load unicode-math and thus lm-math.otf, the subdepth package still has no effect. BUT: The positions of the subscrips is plain wrong in my opinion in the second line, as in M_n^\dagger the subscript is placed *higher* than in the other cases. Which does not happen for the a_i^\dagger.

In total, I see a lot of different placements of the sub/superscripts and I am a bit lost which one is the right one, which one might be a bug and which one is intendedly different – the placement depends on the engine, the font, the size of the nucleus and the size of the superscript. Can anybody help me figure this one out? (What I *want* is the behaviour of pdfLaTeX + subdepth to work in LuaLaTeX + unicode-math)

Best,
Arno

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