# [luatex] Poor Spacing in the \frac Environment

Reinhard Kotucha reinhard.kotucha at web.de
Tue Jan 20 00:23:34 CET 2015

On 2015-01-19 at 15:51:15 -0600, Dan Luecking wrote:

> On 2013-01-18 at 21:59:19 CET, Reinhard Kotucha wrote
>
> >On 2015-01-18 at 23:52:39 -0500, Emil E wrote:
> >
> >  > I've also noted that LuaLaTeX is making the correct adjustments for
> >  > superscripted denominators (ex. a denominator of \delta^{2}), but
> >  > this _only_ occurs on the LuaLaTeX engine with OTF TeX Gyre Pagella
> >  > fonts (it does not happen on LuaLaTeX Computer Modern defaults, or
> >  > in PDFLaTeX).
> >  > This can be seen in the top right section of the linked image,
> >  > on the third and fourth fractions from the right.
> >
> >I don't think that LuaLaTeX does any correction here.  I suppose that
> >the position of the superscript is a little bit too heigh in TG
> >Pagella so that TeX has to lower the complete denominator accordingly.
> >
> >The same happens if you insert the line
> >
> >   \frac{\Big|\delta}{\Big|\gamma} \;
> >
>
> I agree. In fact, I think this is, in fact, a problem with the
> combination of LuaLaTeX with OTF TeX Gyre Pagella and unicode-math.
>
> The various font parameters in cmr, it seems to me, are designed so
> that when "normal" symbols are used with "normal" 'scripts there is
> no shift in the numerators or denominators. This allows the
> baselines and math-axes of numerators and denominators of adjacent
> fractions to be aligned most of the time. That is, the \gamma's in
>    $$\frac{\gamma}{\delta} \frac{\gamma_1}{\delta^2}$$
> line up and the \delta's should also. That is, I think, the ideal
> that Knuth was trying for.

I doubt that Lua[La]TeX and unicode-math are involved at all.  As far
as I can see the font itself is the culprit.  But I'm pretty sure that
Ulrik comes up with a definite answer soon.

Regards,
Reinhard

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