[XeTeX] fonts for units in math mode

[Bruno Voisin]

Le 29 janv. 06 à 21:01, Faisal Moledina a écrit :

> So, to recap, in fontspec.sty, are there defined fonts for math?   
> I'm asking out of the blue, but why should it be necessary to  
> change the math fonts back to Computer Modern for text in math to  
> be displayed properly?

It depends on what you mean by properly. The code re. math fonts in  
fontspec.sty was added by its author (Will Robertson) following a  
suggestion I had done, and which itself was based on the way math  
fonts are handled in slides.cls -- the standard LaTeX class for  
slides. This was done so that text elements in maths are using the  
main text font.

Such considerations do not arise in standard TeX, which uses by  
default the Computer Modern font family -- a complete set of text and  
math fonts all properly matched. As soon as you start replacing the  
text fonts by modern TrueType, PostScript or OpenType fonts, problems  
arise because the default math fonts are still Computer Modern --  
generally considered too thin and spindly to blend well with the  
modern fonts such as Times.

This is why, for example, the mathptmx and mathpazo packages use  
Times and Palatino, respectively, as the text font and use the  
virtual font mechanism to combine characters from this text font with  
characters from Symbol and CMSY in order to produce a reasonably  
matching math font. See /Library/teTeX/share/texmf.tetex/doc/latex/ 
psnfss/psnfss2e.pdf.

>   Also, does anyone know what the "textstyle" option for SIunits is  
> actually for?  Lastly, are there better math fonts out there?

Commercial alternatives are:

- MathTime <http://www.pctex.com/ 
fonts.html#MathTimeProfessional_Fonts>: a complete set of math fonts  
to be used with Times.

- Lucida <http://www.pctex.com/fonts.html#Lucida_Fonts>: a complete  
set of text and math fonts, replacing Computer Modern completely. A  
personal favorite of mine. I use them in conjunction with the OS X  
fonts in XeTeX, using such declarations as:

\usepackage[LY1]{fontenc}
\usepackage[expert,vargreek,lucidasmallscale]{lucidabr}
\usepackage{fontspec}
\setromanfont[Mapping=tex-text]{Optima Regular}

In this way the Lucida fonts are used for maths, and Optima for text.  
The result looks nice to my eyes:

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The Lucida fonts are also available from TUG <http://www.tug.org/ 
store/lucida/>.

Finally, the STIX fonts <http://www.stixfonts.org/> (to be released  
next June -- supposedly) would provide a complete and free set of  
Unicode math fonts in TrueType, PostScript and OpenType formats, and  
their use in TeX should be possible.

Bruno Voisin