unicode
Suppose I have:
\documentclass{article}
\begin{document}
$1 \cdot{1}$
\end{document}
I want to know the glyphs' Unicode for cdot special symbol.
I followed such way.
I've run latex command on my *nix system and perform such command
\show\cdot
after that I see
\cdot=\mathchar"2201.
But that is wrong Unicode for CENTERED DOT character.
How can I determine the mapping rules from 2201 to Unicode?
You should separate input and output. If you want to print a symbol you at first need a font which contains it. If you want to use normal latex (it will work with xelatex too) you can e.g. use the dingbat font to get an anchor. If you want to use the symbol in the input you must declare it (I'm not sure if the ⚓ copy& paste correctly):
\documentclass[12pt]{article}
\usepackage[utf8]{inputenc}
\DeclareUnicodeCharacter{2693}{\anchor}
\usepackage{dingbat}
\begin{document}
\anchor ⚓
\end{document}
With xetex you can use e.g. dejavu sans (if you get the wrong glyph:make sure that you have only version of dejavu sans). Here too you can use commands/other notation if you don't want to use the symbol in the input:
\documentclass[12pt]{article}
\usepackage{fontspec}
\begin{document}
{\fontspec{DejaVu Sans Condensed} ^^^^2693 \char"2693 ⚓}
\end{document}
With lualatex you shouldn't set the encoding to T1, also don't load inputenc and textcomp. If you remove everything it will work:
\documentclass{article}%
\usepackage{parskip}%
\usepackage{graphicx}%
\begin{document}%
\pagestyle{empty}%
13.787±0.020%
\end{document}
Best Answer
You guessed right that the
"2201is a number in hexadecimal representation, but this number is not connected to Unicode (which was born years after Knuth invented mathcodes).The four hexadecimal digits tell TeX that
\cdotis an operation symbol (the first digit2), which must be taken from the font in math family 2 (the second digit), choosing the glyph at slot"01.TeX knows about at most 16 math families, each can define three fonts for the normal size, first level subscripts and superscripts, and second level sub(super)scripts.
Family 0 fonts contain the upright letters, family 1 the math italic ones; family 2 fonts contain the most common math symbols; finally family 3 fonts contain the "big" symbols such as extensible parentheses.
These four families are compulsory if one wants to typeset math formulas, as TeX relies on parameters from these fonts to do its job. Other families can be (and are) defined by the LaTeX kernel (for
\mathbf,\mathsfand so on) or by additional packages (for example stmaryrd).There's no connection whatsoever between math codes and Unicode.
The XeTeX and LuaTeX engines define new primitives for dealing with Unicode math fonts, but that's another story.
TeX fonts contain at most 256 glyphs, the standard math fonts only 128. Their tables are laid out in the TeXbook or in TeX by Topic (on TeX Live this one is available with
texdoc texbytopic). You can produce yourself the font tables by typesetting the following document: