[XeTeX] Font variant selection in Fontspec/Mathspec options incomplete

[Ross Moore]

Hi Pinfeng,

Sent from my iPad

On 13/11/2010, at 10:49 PM, "Christian Schmidt" <c.schmidt at dlgs.ioer.de> wrote:

> Hi Ross,
> 
>>> Though, this leads me to the additional note, that in math mode---which is typically set in italics---, the use of \mathbf{x} does not produce a bold italic variant but rather only a bold upright variant of x in this case.
> 
>> This is the way it has always been in LaTeX.
>> It should not be changed, else this will affect millions of existing documents.
> 
> I wasn't aware about this issue. In normal text mode, italic and bold font selections work complementary... so I expected the same behavior in math mode too. I can't really understand these differing approaches.

It is historical, due partly to the limited set of font styles available for mathematics with TeX.
But this is more of a design choice, rather than a limitation.

The approach adopted in the Mathematical Publishing and Math Knowledge Management is that typestyles are not something that is open to the whim of the author. You only use a fancy variant when there is a real need for it, with regard to the meaning that the symbol is to convey.
  
For example, bold math might be for vectors, with ordinary math italic used for individual components. With some symbols, a bold math italic might not print sufficiently differently (especially on poor quality paper) to a non-bold variant, to maintain the clarity of meaning that you want with mathematics. After repeated photo-copying, you would certainly get into trouble.
This was the technology of the later part of the 20th century, and many people still work that way. Indeed, it hasn't really changed that much yet. And will not change until everybody has an iPad or similar technology. And for this to work well you need every symbol to be tagged with it's meaning --- this is more important for the transmission of meaning and understanding, than is having a plethora of different visual forms. 


> 
>>> If I use the \pmb{x} or \bm{x} commands instead for instance, XeLaTeX produces a bold italic looking variant of the letter x. In closer inspection, however, the bold italic x is nothing else than a normal italic x superimposed on another one with a slight offset...
> 
>> Yes. This is a hack to compensate for lack of math fonts.
>> This kind of thing should no longer be necessary with proper OTF math fonts, but you need new macros to refer to the desired characters.
>> This is what Unicode-math and math spec are for. They completely rewrite how LaTeX handles mathematics with such fonts. It is a massive job, not yet completed.
> 
> I already had a look at the Unicode-math package, but as I understood is it used instead of Mathspec, which however would provide better customization I think.

Surely math spec is an interface to aspects of Unicode-math.

> 
>>> Is there a way to use the regular \mathbf{...} command to have bold italic math?
> 
>> Isn't there a command \mathbfit or similar spelling?
> 
> Thanks a lot for this hint. Even after "googling" for bold fonts in math before I haven't come across this command. I tried it out and it totally works! :)
> 
>> But better is to define a macro for the concepts that require use of such bold symbols;
>> E.g.  \newcommand{\xx}{\mathbfit{x}}and use these within the body of your document.
> 
> Yeah, I might do that.
> 
>> Hope this helps,
> 
>>       Ross
> 
> Absolutely.
> 
> Thanks a lot for the help.


   All the best.

            Ross
> 
> Pinfeng
> 
> 
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