读懂 TeX 的 Font Warning

引入

闲来无事，在编译的一个TeX文档的过程中看到了如下的警告:

LaTeX Font Warning: Font shape `TU/NewCM10-Book.otf(2)/m/it' undefined
(Font)              using `TU/NewCM10-Book.otf(2)/m/n' instead on input line 43


LaTeX Font Warning: Font shape `TU/NewCM10-Book.otf(2)/b/n' undefined
(Font)              using `TU/NewCM10-Book.otf(2)/m/n' instead on input line 55
.


LaTeX Font Warning: Font shape `TU/NewCM10-Book.otf(2)/m/sl' undefined
(Font)              using `TU/NewCM10-Book.otf(2)/m/it' instead on input line 5
8.

那么问题来了，这个里面的 /m/it, /b/n, /m/sl 是什么意思 ?

参考

本博客内容参考(抄袭)内容过多，但是大致可以例举如下:

• TeX SE 的回答 1
• TeX SE visaul markup
• The LaTeX Companion-III part1 9.2-Understanding font characteristics
• The LaTeX Companion-III part1 9.5-Standard LATEX font support
• The LaTeX Companion-III part1-9.4.1-Defining new alphabet identifiers

正文

In NFSS, there are four font parameters：

• the encoding
  • OT1 encoding: The fonts that were originally distributed with TEX had only 128 glyphs per font and therefore did not include any accented characters as individual glyphs.
  • T1 encoding : As an alternative encoding, the TEX user community defined a 256-character encoding called T1 that enables TEX to typeset correctly (with proper hyphenation and kerning) in more than 30 languages based on the Latin alphabet
  • TU encoding: use Unicode fonts and thus use Unicode as the encoding, made the default if $\rm\LaTeX$ is used with such an engine, like xelatex.
• the font family
  • lmr: Latin Modern Roman
  • cmss: Computer Modern Sans Serif
  • …
• the series: typeface of current font
  • m: selects a font with medium values for the width and the weight
  • b/x: switches to a bolder series, x refers to ‘extend’.
• the shape:
  • n: The normal(upright) shape
  • it: The italic shape
  • sl: The slanted or oblique shape
  • sc: The Small Caps shape
  • The swash letter shape

采用缩写的具体历史原理是因为MS-DOS文件系统的限制，见如下:

This naming scheme dates back to when MS-DOS limited all filenames to be eight characters, a dot, and a three-character file type, so they had to be terse.

关于这个属于的区别: 可以参见下面的这些命令: The visual \textXX commands will change 3 axes of the text: shape, family and weight.

• The shape axis covers: \textup, \textit, \textsc and \textsl
• The family axis covers: \textrm, \textsf, \texttt
• The weight axis covers: \textbf, \textmd

Table

下面从 The LaTeX Companion-3rd edition 中截取了两张表格用于对上面的内容进行一个补充:

Math Alphabets

在了解如上所述的基本字体知识后，我们可以对数学公式下手了. 你也许经常看到下面这个命令:

\DeclareMathAlphabet{cmd}{encoding}{family}{series}{shape}

这个玩意儿到底是什么意思? 其实你在看了前面的 看懂TeX的字体警告 之后应该就能看懂这个命令了.

new identifier

Suppose that you want to make a slanted sans serif typeface available as a math alphabet. You will find that the Computer Modern Sans family, for example, consists of a medium series with upright and slanted shapes. Then declare and use it as follows:

\DeclareMathAlphabet{\mathsfsl}{T1}{cmss}{m}{sl}

We demonstrate this with the formula
\begin{equation}
\sum \mathsfsl{A}_{i} = a \tan \beta
\end{equation}

redefine identifier

It is also possible to redefine an existing math alphabet identifier in a package file or in the preamble of your document. For example, the declaration

\DeclareMathAlphabet{\mathsf}{T1}{qag}{m}{n}

Then \mathsf will switch to Adventor (Avant Garde) in your formulas.

如果一个math alphabet 已经被某一个symbol font 加载了，那么最好使用命令 \DeclareSymbolFontAlphabet，这样可以节约资源