[NTG-context] LuaTeX and Unicode Math

Aditya Mahajan adityam at umich.edu
Wed Oct 3 02:26:33 CEST 2007


Hi,

> While trying to convert some stuff from HTML to PDF (using LuaTeX) I
> have noticed some minor problems: unicode math characters work OK in
> text mode (under assumption that the font has them), but not in math
> mode. In pdfTeX they work OK in both cases. (That behaviour is
> expected, but not necessary desired.)

I know about this, and this is one of the main reason that I am still 
using pdftex for day to day work.  I have become used to typing most 
of my math in unicode, and now none of it works (with luatex). But I 
have been too busy to actually try to understand what is happening 
behind the scences.

> Is there any cure to it?

AFAIK, luatex has not toched on the math handling of tex yet. There 
are some old ideas on how TeX's math support can be improved, and with 
luatex that is a real possibility. I am sure that at some stage, once 
some aspects of the lua functionality are more stable, this will be 
looked into. It makes sense to finalize mkiv support only after that.

> I could/should solve the problem with better handling of xml entities
> or with fallbacks (if φ is not present in font, use \phi etc.), but I
> don't know how to do either of them.
>
> I would normally say something like
>   \chardef`φ=\active
>   \defφ{\phi}
> to solve the problem, but that doesn't work when doing XML conversion.

Actually, for a unicode aware engine it should be the other way around

\def\phi{φ}

That is, all definemathcommand be changed to something like

\definemathcharacter[φ][<font:location>]

and so on. But my guess is that this will need a overhaul of the math 
character encoding. Again, that is something which I do not understand 
at the moment.

Aditya


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