Entering Unicode characters in LaTeX

Question

How do I enter Unicode characters in LaTeX? What packages do I need to install and what escape sequence do I type to specify Unicode characters in an ASCII source file?

Answer 1

Have you considered using XeTeX? This is an adaptation of TeX that adds Unicode support, and is included in the latest TeX Live and MiKTeX distributions. This Wikipedia article gives a good introduction.

Answer 2

"Unicode" in this context could mean either in the input or in the output. I assume you're looking to insert something like "©" into your source and have it do something meaningful.

For full support for unicode input and unicode fonts, take a look at XeTeX; it's easy to get started — just select an appropriate font and the unicode characters in your input are directly typeset as unicode glyphs in the output. Switching engines is not always a possibility, however, and sometimes you'll want to stick with pdfTeX for its other useful features.

The best that regular LaTeX (i.e., based from pdfTeX in a modern distribution) can do is recognise UTF-8 sequences in the text and expand macros based on what it sees. Load the inputenc package to select the UTF-8 input encoding:

\usepackage[utf8]{inputenc}

Note that the resulting input file must not have a byte-order mark (BOM) at the beginning, or else it won't compile. (You can also use the [utf8x] option which has more extensive coverage but is not as well supported. I don't have any experience using this option.)

To define behaviour for unicode characters, use the \DeclareUnicodeCharacter command that is then defined. Here's an example for binding the control sequence \dash to the input character "—"; i.e., a literal em-dash, U+2014, in the source:

\DeclareUnicodeCharacter{2014}{\dash}

\dash can then be defined in the usual manner; I use:

\DeclareRobustCommand\dash{%
  \unskip\nobreak\thinspace\textemdash\allowbreak\thinspace\ignorespaces}

This defines a dash that has a small space on either side and will only allow a line break after it.

Answer 3

This is a minimal example that finally worked for me without using XeTeX:

\documentclass{article}
\usepackage[mathletters]{ucs}
\usepackage[utf8x]{inputenc}

\begin{document}
    The vorticity $ω$ is defined as $ω = ∇ × u$.
\end{document}

Answer 4

Try \char"hexcode like \char"2012 for the ‒ (figure-dash). This command works in XeLaTeX and probably other engines

Answer 5

In case anyone is not satisfied with any of the answers: I just had the same problem and came up with my own little solution. I didn't want to dig into another distribution but stay with pdflatex. So I created a textfield in inkscape, put the character in, cropped it, and saved as pdf. You can include the pdf in your document like this:

\includegraphics[width=1em]{symbol.pdf}

Answer 6

In order to use XeLaTeX (and even both pdflatex and xelatex on the same document), you can use the simple unixode package:

\documentclass{article}
\usepackage{unixode}

\begin{document}
    The vorticity $ω$ is defined as $ω = ∇ × u$.
\end{document}

You may then compile your document either with pdflatex or with xelatex.

Note: the package is in development; the aim is to support as many unicode equivalents as possible.

Answer 7

As of 2020, Arthur Reutenauer says that XeTeX has “gone into maintenance mode,” and the future of TeX development is LuaTeX. I would therefore recommend using LuaTeX when you can, then XeTeX if you have to, and PDFTeX if it’s all that your publisher supports.

Now that LuaTeX supports complex scripts, the main XeTeX feature I use that LuaTeX does not have (as of July 2020) is interchar tokens. There are, on the other hand, many LuaTeX features that XeTeX does not have. I use microtype font expansion in nearly every document I create.

If you’re asking what syntax to use to enter Unicode characters, you can use the syntax ^^^^abcd for U+ABCD, \char"ABCD, \symbol{"ABCD}, or any of the macros defined by the LaTeX kernel or unicode-math.

Answer 8

As of today, both XeTeX and LuaTeX will let you input unicode without complaining.

Answer 9

Sorry, I'm not an expert on this, but hope I can at least provide some useful leads.

A lot of the early multi-lingual support for LaTeX predates the widespread adoption of Unicode, although it looks like there's been some consolidation around Unicode recently. So you might find something useful in specific language support packages, e.g. CJK LaTeX (for Chinese, Japanese and Korean).

Another Unicode package for LaTeX has a new name (formerly unicode; now ucs). For a list of Unicode packages, see https://ctan.org/topic/unicode .

You might also have a look at the excellent book The LaTeX Companion, which includes a section on multilingual text.

Answer 10

This answer explains more of the background "what happens internally, and why it seems to be so complex".

	PDFTeX	XeTeX/LuaTeX
Text mode	Maintained by LaTeX team (inputenc), compose accent on characters	Available by default, if font has character
Math mode (legacy font)	Not officially supported	Not officially supported
Math mode (OpenType math font)	Not available	Maintained by LaTeX team (unicode-math)

---

Text mode

PDFTeX

It's commonly said that "PDFTeX does not support Unicode", but

• it doesn't mean you can't type a non-ASCII character like ǫ and get that character in the output.

What it means is

• Each UTF-8 character (byte sequence) is interpreted as 2/3 character tokens, not 1

• TeX cannot natively "pick character at position X from OpenType font Y and put on the paper". (source 1 2 3 )

  However, it can pick character at position X from old-style (METAFONT) font file Y, and so it's possible to "convert" a OpenType font to old font files (each font file contains maximum 256 characters). See CJK package for an example.

More commonly, characters with accents are composed from a letter and an accent, which is what inputenc package does.

Particular example:

• In the case of the letter ǫ, internally TeX use inputenc library to "convert" the 2 bytes c7 ab to the macro \k o, which puts the character o and the hook on the PDF page.

  If you copy the content on the PDF page, you'll get o˛ – the character o and the hook separately.

  _{(it's possible to make the copied content and the displayed content different, see comment, but that's not the point here.)}

XeTeX/LuaTeX

In this case, the program can typeset the character directly so usually there's no problem.

Special case: if the font does not have the character (for example the character α in the default Latin Modern font), it will drop an empty space in. See https://tex.stackexchange.com/a/377729/250119.

Math mode

PDFTeX

The LaTeX team does not define in the inputenc package – the most popular one used to process Unicode input, so if you use e.g. ∈ in math mode it will not work.

Compare:

Character	utf8	utf8x (ucs)	[mathletters]{ucs}
ǫ	good	good	good
∈	not supported	\ensuremath{\in}	same
α	not supported (requires babel or similar)	\textalpha (still requires babel or similar)	\ensuremath{\alpha}
ⁿ	not supported	\textsuperscript n	\ensuremath{^n}

As mentioned in ucs package documentation of mathletters option:

This option is disabled by default, because using math greek in a normal text does not look good

XeTeX/LuaTeX

Without unicode-math, the engine uses traditional math font ^source, so it has the same problem as above.

With unicode-math, the engine uses Latin Modern Math font (by default) _{this also explains why there are some differences between the output with and without unicode-math – because the glyph in Latin Modern math font is different}, so you can use characters like α in math mode without any problem.

Internally, the package unicode-math:

• defines the mathcode for each Unicode character (unlike PDFTeX, it's not necessary to make these characters active, because the code point of the character to be typeset is the same as the input character), and
• define the corresponding command (\alpha, \varnothing, \mathbb) to translate to the corresponding Unicode character.

Use Unicode input with legacy math font

Recall that this is not supported by the LaTeX team.

• find some package that defines it

  • utf8x option (ucs package). See comparison.
  • inputenx package has some math characters, using it depends on some removed inpmath package (now source code can be found on the Internet Archive. See also comparison.
  • unixode package for example, mentioned in other answer.

• defining the characters yourself

• find some suitable table of characters then define it yourself:

  • from a pull request to the unixode repository. Has approximately 2500 symbols.

  • from ucs source code. Has approximately 700 (math) symbols. _{(based on counting number of lines with ensuremath in the generated .def files)}

  • a list from flowfram / texparser source code.

  • from unicode-math source code. Has approximately 2500 symbols.

    Note that, as explained above, this table is meant to define the command to map to the Unicode character, so

    • there are some Unicode characters that is listed twice.
    • some escape sequences are not defined in the default "legacy math" mode (for example \muprho "math upright rho")

  • from unixode source code. Has approximately 100 symbols.

Answer 11

If you are looking for unicode characters defined in a standard font, you can do: Use either XeLaTeX or LuaLaTeX.

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{fontspec}
\begin{document}
Print some leaves: {\fontspec{Symbola} %the font name
                                      \symbol{"1F343}} %unicode symbol code                  
\end{document}

Answer 12

This question is really ambiguous, and I believe the answers are to the wrong interpretation. To have LaTeX handle Unicode is what is being answered, what I understand is being asked is how to enter such characters into the file. And that depends on the editor used... I've even copy&pasted some from Wikipedia pages into xemacs to go around that. The methods given in the Unicode FAQ clash with xemacs definitions or get interpreted at random by gnome-terminal :-(