[XeTeX] Using OpenType MathPi?

[Jonathan Kew]

On 14 Jun 2004, at 2:34 pm, J P Blevins wrote:

> Using the Type 1 version of MathematicalPi produces curious offsets,

This would be because either (a) no encoding (.enc) file is specified 
in the psfonts.map file, and the glyph list of the font doesn't happen 
to correspond nicely to the character coding used; or (b) there is an 
.enc file, but xdv2pdf is unable to apply it anyway because there's no 
'post' table with glyph names in the font.

>  and
> loading the mathtime package yields an error,

What kind of error, just out of curiosity?

>  so I am trying to use the
> OpenType font Mathematical Pi LT Std, which has many of the characters 
> I
> need.
>
> However, I can't see how to get access to these characters.
> Mathblackboard 'R', for example, \U00211D, shows up in the character
> palette, and can be inserted into a BBEdit text file with a UTF-8 or
> UTF-16 encoding, and it is processed by invoking XeTeX within TeXShop
> using the corresponding encodings. Yet the character displays as an
> unprintable character in the PDF output.

I'm unclear how you're loading this font; are you (a) accessing it 
directly as an OT font, with
	\font\mathpi="Mathematical Pi LT Std" at 10pt
or some equivalent, or are you (b) loading a .tfm file that is supposed 
to correspond to the OT font?

If it's case (a), then any of
	\char"211D
	^^^^211d
	literal Unicode character
ought to work; I don't have that font myself so I can't try it 
directly, but normally that's all there is to it.

If (b), then how is the encoding of the .tfm file (which would be a 
legacy 8-bit encoding of some kind) supposed to relate to the Unicode 
characters in the OpenType font? You'd need an appropriate .enc file 
specified in psfonts.map for this to work, I think. (And the OT font 
will have to be re-encodable by xdv2pdf, which means it needs a full 
'post' table; not all OT fonts have this. That seems to be a recurring 
theme of font encoding problems here....)

>
> So how does one get XeTeX to access to math characters, etc., in an
> OpenType font? If this is a RTFM question, I'd appreciate references.

There is no M for you to R, yet. :-) So far, XeTeX is documented 
primarily by example; if you've looked at the Sample Files package, and 
in particular the XeTeX Notes file, you've seen pretty much what there 
is. That, and the archives of this list, I suppose.

HTH,

Jonathan