[XeTeX] fontspec v1.7

[Hans Hagen]

Will Robertson wrote:
> Ross Moore wrote:
> 
>> how shall we proceed to implement mathematics
>> properly ?
>>
>> Indeed, what does *properly* actually mean now ?
> 
> 
> I would suggest that *properly* means that a unicode maths font can be 
> set up in XeTeX to typeset maths in a maths environment, up to the level 
> of writing in the literal glyphs if that is desired (but control 
> sequences in general would be easier).
> 
> There are many problems with this, the biggest, as I see it, being that 
> TeX needs all those extra font dimensions that unicode fonts simply 
> lack, as far as I am aware. But if I recall correctly, Michael Downes 
> wrote a package that dealt with maths doing all of the spacing 
> explicitly, so it's at least possible in theory. (breqn?)
> 
> But this is a further reaching goal. The problem started with fontspec 
> doing bad things with maths, and this is something that needs to be fixed.
> 
> First: do we actually want \mathrm to take the font of the text?
> 
> If so, then we simply need to remove the Knuthian assumptions that the 
> maths font can take various accents and analphabetics from the text font 
> and replace those definitions with fixed references to glyphs in a 
> similarly old-fashioned font. So, if no other maths fonts are loaded, 
> then the maths accents should be defined in terms of Computer Modern, 
> and probably similarly with euler. lucbmath I haven't yet looked through 
> but I'm sure that situation's similar.
> 
> Do we agree so far? For now, maths is strictly legacy, and the maths 
> font packages need to be patched in XeLaTeX to reflect this. Beyond this 
> I really don't know enough of the details to comment, yet...

there is work in progress (was discussed at eurotex) to come to a new math font 
specification; will take some time;

somehow i feel that the assumption that determining from the glyphs how spacing 
should look (i.e. is sin a function name (roman) or is it a multiplication of 
three variables) is not doable and comparable to assuming that using a greek 
character means that we're typesetting greek (or making xetex trigger german 
hyphenation due to an ediaeresis in the text stream). The fact that that a 
symbol (glygh) has to do with math does ot imply that math is involved.

Hans


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