[XeTeX] Re: [MacTeX] XeTeX
Ross Moore
ross at ics.mq.edu.au
Wed Apr 14 04:08:25 CEST 2004
On 14/04/2004, at 12:54 AM, Ross Moore wrote:
> Here's what I've just discovered:
>
> Using the \mathcode settings from plain.tex :
>
> \mathcode`\(="4028
> 4*16^6 + 0*16^5 + 2*16 + 8 = 67108904 (XeTeX gives this)
> \mathcode`\=="303D
> 3*16^6 + 0*16^5 + 3*16 + 13 = 50331709 (XeTeX gives this)
> but sometimes the shift is different:
> \mathcode`\.="013A
> 0*16^5 + 1*16^4 + 3*16 + 10 = 65594 (XeTeX gives this)
> \mathcode`\-="2200
> 2*16^6 + 2*16^4 + 0*16 + 0 = 33685504 (XeTeX gives this)
Doh!
because of the zeros, these are all consistent with:
?*16^6 + ?*16^4 + ?*16 + ?
as confirmed by:
\mathcode`\^^A="3223 % \downarrow
3*16^3 + 2*16^2 + 2*16 + 3 = 12835 (TeX gives this)
3*16^6 + 2*16^4 + 2*16 + 3 = 50462755 (XeTeX gives this)
(Hmm; at ~1:00am this simple explanation escaped me!)
So it looks like the \mathcode numbers have been built from
the 3 separate pieces of information
e.g. "3223 = 3 2 23 (each in Hexadecimal)
which xetex stores (or reads back) as: "03 "02 "0023
Also, the mathcode "8000 trick is used by several
LaTeX packages. For testing this:
\count255="8000
\showthe\count255
{\obeyspaces%
\mathcode`\ ="8000 % \space
\count255=\mathcode`\ % space
\showthe\count255%
}%
TeX gives: 32768 = 2^{15} = "8000
XeTeX gives: 134217728 = 2^{27} = 8 x 16^6 = "08 00 0000
> So the bits are being mis-interpreted, either on setting
> the \mathcode , or upon reading back its value.
Over to you now Jonathan --- welcome to the list !
Cheers
Ross
------------------------------------------------------------------------
Ross Moore ross at maths.mq.edu.au
Mathematics Department office: E7A-419
Macquarie University tel: +61 +2 9850 8955
Sydney, Australia fax: +61 +2 9850 8114
------------------------------------------------------------------------
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