[XeTeX] Unicode, infinity, TeXShop and XeTeX

[Bruno Voisin]

Le 18 févr. 05, à 12:36, Stephen Moye a écrit :

> I am using Hoefler Text in plain TeX in TeXShop. I need to use the 
> 'infinity' sign (in Unicode Mathematical Oerators, position 2210E, at 
> least according to the Mac Character Palette) and cannot for the life 
> of me figure out how to get it.
>
> This is that last piece of a puzzle I've been working on, and any 
> pointers would be gratefully recieved.

If you want to use your infinity sign in text, it's as easy as writing 
(the infinity character is told by the character palette to be at 
position 221E):

	\font\test="Lucida Grande"
	\chardef\textinfty="221E
	\test My nice \textinfty
	\bye

This is possible because XeTeX generalizes TeX's \chardef primitive to 
use 4-digit hexadecimal character codes (appropriate for 16-bit Unicode 
fonts) instead of just 2-digit codes (appropriate for 8-bit fonts) as 
in the TeXbook.

However, there is no such generalization for \mathchardef, which 
prevents you from using:

	\mathchardef\infty="02221E

which would be the logical Unicode extension of plain TeX's default:

	\mathchardef\infty="0231

where the initial 0 means class 0 (= ordinary characters) and the 
following 2 means family 2 (= math symbols). It's probably better 
anyway in this case, since mixing the infinity sign from a Unicode OS X 
font with the mathematical characters from a TeX math font (generally 
Computer Modern, noticeably thinner) would result in suboptimal output.

Bruno Voisin