# [XeTeX] fontspec v1.7

Will Robertson will at guerilla.net.au
Sun Jul 3 08:47:29 CEST 2005

On 23 Jun 2005, at 8:46 PM, Ross Moore wrote:

> On 23/06/2005, at 5:58 PM, Hans Hagen wrote:
>> Will Robertson wrote:
>>> First: do we actually want \mathrm to take the font of the text?
>
> Not necessarily; indeed, probably not.

Indeed?
I was basing my work on the assumption that this is what has been
done previously (i.e., both euler.sty and lucbmath.sty define \mathrm
as \rmdefault). I guess it all comes down to how you're mix-and-
matching.

>> 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
>
> Certainly it is not doable from the glyphs alone; but if you take
> into account
> that we are inside math-mode, and that an upright font is being
> used, then
> you can deduce what is intended.

Unless there is an unforeseen revolution in keyboard technology, I
think we'll be writing in terms of macros for quite some time. And
obviously changes in font need to be tagged logically, so I don't see
a problem here.

> The Code2001 font has "Alphanumeric Mathematical Symbols",
> which include math-italic, upright, bold, and bold-italic
> variants.
>
> XeTeX *can* typeset with these --- contrary to what I said in
> a previous message. You need to use combining pairs.
> ...
> It would not be unreasonable to have XeTeX supply these code-points
> when in math-mode, provided there is a font available to support them
> (such as Code2001).
>
> However, XeTeX would still need to supply the correct spacing for
> mathematics, just as TeX does already.

We have the problem now (don't we?) of not really knowing that much
about the shape of the maths glyphs, as opposed to Knuth's maths
fonts with 16 various font dimensions. That might be a bit of a
tricky problem to solve.

> Note that there is no  math-upright (of medium weight).
> Thus  \mathrm  would use ordinary characters, with their usual
> spacing.
> This need *not* be the normal text-font for the document
>    (e.g., use Code2000  when math is in  Code2001 , say).
> Of course \text is different from \mathrm , being really a temporary
> escape out of math-mode, back into text-mode.
> (Authors need to be educated to respect this distinction!)

And now we come full circle back to the topic of mathrm.
It seems reasonable to me that there is actually no such thing as
math upright, but rather a matching text font is often used to label
functions and to tag variables with super/subscripts.

Since for now we don't have a way to properly use unicode maths
fonts, I'm going to stick by the convention of using the default text
fonts for the default math text' fonts, but I'll add a package
option to either turn it on or off (haven't decided yet).

I can't really see what the next step needs to be to get to be able
to typeset maths with a unicode maths font.

Will

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