12 Fuentes en fórmulas

For most symbols in a formula, the font used for a glyph cannot be changed by a font declaration as it can be in text. Indeed, there is no concept of, for example, an italic plus sign or a small capital less than sign.

One exception involves the letters of the Latin alphabet, whose appearance can be altered by the use of math alphabet identifier commands such as . The commands provided by standard LaTEX for this purpose are discussed in Section 9.4; in the first section of this chapter we introduce a few more and discuss their use in some detail.

Another exception relates to the use of bold versions of arbitrary symbols to produce distinct symbols with new meanings. This potentially doubles the number of symbols available, as boldness can be a recognizable attribute of a glyph for nearly every shape: depending on the font family, even “<” is noticeably different from “<”. Although there is a command, the concept of a math alphabet identifier cannot be extended to cover bold symbols— better solutions are the topic of the second section.

To change the overall appearance of the mathematics in a document, the best approach is to replace all the fonts used to typeset formulas. This is usually done in the preamble of a document by loading a (set of) suitable packages, such as those discussed in Section 12.3 starting on page 238.

In the world of text fonts (Chapter 10) there is a clear separation between fonts suitable only for use with pdfTEX and fonts for exclusive use in Unicode engines. Fonts for pdfTEX are available as 8-bit fonts, encoded in OT1, T1, or some other 8-bit font encoding from Table 9.18 on page →I 737 and typically available as Type-1 or METAFONT fonts. In contrast, OpenType or TrueType fonts are usable only with X TE EX or LuaTEX and are encoded in the TU font encoding.1,2

For symbol fonts this is not the case, at least in one direction: it is easily possible to use an 8-bit symbol font, e.g., MarVoSym, originally designed for use with pdfTEX, with one of the Unicode engines.

Given that formulas largely consist of fixed symbols together with a few alphabetical characters and that there have not been (many) Unicode fonts dedicated to mathematics (i.e., fonts that contain the mathematical symbols in their appropriate Unicode slots), it should come as no surprise that the Unicode engines have been designed to work with traditional TEX math fonts.

This has changed in recent years, and while developing OpenType Math fonts (compared to Text fonts) remains a niche market, there are now a number of fonts available that make it interesting to provide a LaTEX math setup that directly uses such fonts. Such a setup is available with the unicode-math package by Will Robertson, and we will describe it in Section 12.4 on page 253.

In the final section of this chapter, starting at page 261, we showcase the effects of extensive changes to documents on a sample page of mathematics, made with just a few keystrokes. It uses the same input material typeset with both Computer Modern Math fonts (the default in LaTEX) and nearly 50 other font family setups for text and mathematics. All of the fonts used are readily available and, except for Lucida fonts, provided free of charge.