# TeX

Developer(s) | Donald Knuth |
---|---|

Initial release | 1978 |

Stable release | TeX Live 2024 ^{[1]}
/ 13 March 2024 |

Repository | |

Written in | Permissive free software |

Website | tug |

Filename extension |
.tex |
---|---|

Internet media type |
application/x-tex ^{[a]} |

Initial release | 1978 |

Type of format | Document file format |

**TeX** (

^{[3]}

TeX is widely used in

^{[b]}the previously favored formatting system, in most Unix installations. It is also used for many other typesetting tasks, especially in the form of LaTeX, ConTeXt, and other macro

TeX was designed with two main goals in mind: to allow anybody to produce high-quality books with minimal effort, and to provide a system that would give exactly the same results on all computers, at any point in time (together with the Metafont language for font description and the Computer Modern family of typefaces).^{[4]} TeX is free software, which made it accessible to a wide range of users.

## History

When the first paper volume of Knuth's *The Art of Computer Programming* was published in 1968,^{[5]} it was typeset using hot metal typesetting on a Monotype machine. This method, dating back to the 19th century, produced a "classic style" appreciated by Knuth.^{[6]} When the second edition was published, in 1976, the whole book had to be typeset again because the Monotype technology had been largely replaced by phototypesetting, and the original fonts were no longer available. When Knuth received the galley proofs of the new book on 30 March 1977, he found them inferior. Disappointed, Knuth set out to design his own typesetting system.

Knuth saw for the first time the output of a high-quality digital typesetting system, and became interested in digital typography. On 13 May 1977, he wrote a memo to himself describing the basic features of TeX.^{}

### WEB and literate programming

For later versions of TeX, Knuth invented the concept of

### TeX82

TeX82, a new version of TeX rewritten from scratch, was published in 1982. Among other changes, the original

^{[12]}

Since version 3, TeX has used an idiosyncratic

^{[13]}The design was frozen after version 3.0, and no new feature or fundamental change will be added, so all newer versions will contain only bug fixes.

^{[14]}Even though Donald Knuth himself has suggested a few areas in which TeX could have been improved, he indicated that he firmly believes that having an unchanged system that will produce the same output now and in the future is more important than introducing new features. For this reason, he has stated that the "absolutely final change (to be made after my death)" will be to change the version number to π, at which point all remaining bugs will become features.

^{[15]}Likewise, versions of Metafont after 2.0 asymptotically approach e (currently at 2.7182818), and a similar change will be applied after Knuth's death.

^{[14]}

### Public domain

Since the source code of TeX is essentially in the

## Use of TeX

In several technical fields such as computer science, mathematics, engineering and physics, TeX has become a de facto standard. Many thousands of books have been published using TeX, including books published by Addison-Wesley, Cambridge University Press, Elsevier, Oxford University Press, and Springer. Numerous journals in these fields are produced using TeX or LaTeX, allowing authors to submit their raw manuscript written in TeX.^{[18]} While many publications in other fields, including dictionaries and legal publications, have been produced using TeX, it has not been as successful as in the more technical fields, as TeX was primarily designed to typeset mathematics.

When he designed TeX, Donald Knuth did not believe that a single typesetting system would fit everyone's needs; instead, he designed many hooks inside the program so that it would be possible to write extensions, and released the source code, hoping that the publishers would design versions tailoring to their own needs. While such extensions have been created (including some by Knuth himself),^{[17]} most people have extended TeX only using macros and it has remained a system associated with technical typesetting.^{[19]}^{[20]}

## Typesetting system

TeX commands commonly start with a

^{[21]}

The TeX system has precise knowledge of the sizes of all characters and symbols, and using this information, it computes the optimal arrangement of letters per line and lines per page. It then produces a

`amsmath`

, `amssymb`

) and the "AMS document classes" (e.g., `amsart`

, `amsbook`

). This is then referred to as AMS-LaTeX.^{[25]}Other formats include ConTeXt, used primarily for desktop publishing and written mostly by Hans Hagen at Pragma

### How it is run

A sample

```
Hello, World
\bye % marks the end of the file; not shown in the final output
```

This might be in a file *myfile.tex*, as *.tex* is a common

### Mathematical example

TeX provides a different text syntax specifically for mathematical formulas. For example, the quadratic formula (which is the solution of the quadratic equation) appears as:

Source code | Renders as |
---|---|

```
The quadratic formula is $-b \pm \sqrt{b^2 - 4ac} \over 2a$
\bye
``` |

The formula is printed in a way a person would write by hand, or typeset the equation. In a document, entering *mathematics mode* is done by starting with a $ symbol, then entering a formula in TeX syntax, and closing again with another of the same symbol. Knuth explained in jest that he chose the dollar sign to indicate the beginning and end of mathematical mode in plain TeX because typesetting mathematics was traditionally supposed to be expensive.^{[26]} *Display mathematics* (mathematics presented centered on a new line) is similar but uses $$ instead of a single $ symbol. For example, the above with the quadratic formula in display math:

Source code | Renders as |
---|---|

```
The quadratic formula is $$-b \pm \sqrt{b^2 - 4ac} \over 2a$$
\bye
``` |

(The examples here are not actually rendered with TeX; spacing, character sizes, and all else may differ.)

## Aspects

The TeX software incorporates several aspects that were not available, or were of lower quality, in other typesetting programs at the time when TeX was released. Some of the innovations are based on interesting algorithms, and have led to several theses for Knuth's students. While some of these discoveries have now been incorporated into other typesetting programs, others, such as the rules for mathematical spacing, are still unique.

### Mathematical spacing

Since the primary goal of the TeX language is high-quality typesetting for publishers of books, Knuth gave a lot of attention to the spacing rules for mathematical formulae.^{[27]}^{[28]} He took three bodies of work that he considered to be standards of excellence for mathematical typography: the books typeset by the Addison-Wesley Publishing house (the publisher of *The Art of Computer Programming*) under the supervision of Hans Wolf; editions of the mathematical journal *Acta Mathematica* dating from around 1910; and a copy of *Indagationes Mathematicae*, a Dutch mathematics journal. Knuth looked closely at these printed papers to sort out and look for a set of rules for spacing.^{[29]} While TeX provides some basic rules and the tools needed to specify proper spacing, the exact parameters depend on the font used to typeset the formula. For example, the spacing for Knuth's Computer Modern fonts has been precisely fine-tuned over the years and is now set; but when other fonts, such as AMS Euler, were used by Knuth for the first time, new spacing parameters had to be defined.^{[30]}

The typesetting of math in TeX is not without criticism, particularly with respect to technical details of the font metrics, which were designed in an era when significant attention was paid to storage requirements. This resulted in some "hacks" overloading some fields, which in turn required other "hacks". On an aesthetics level, the rendering of radicals has also been criticized.^{}

^{[32]}

^{[33]}

^{[34]}

### Hyphenation and justification

In comparison with manual typesetting, the problem of

*first-fit*approach, where the breakpoints for each line are determined one after the other, and no breakpoint is changed after it has been chosen.

^{[35]}Such a system is not able to define a breakpoint depending on the effect that it will have on the following lines. In comparison, the

*total-fit*line-breaking algorithm used by TeX and developed by Donald Knuth and Michael Plass

^{[36]}

*all*the possible breakpoints in a paragraph, and finds the combination of line breaks that will produce the most globally pleasing arrangement.

Formally, the algorithm defines a value called *badness* associated with each possible line break; the badness is increased if the spaces on the line must stretch or shrink too much to make the line the correct width. Penalties are added if a breakpoint is particularly undesirable: for example, if a word must be hyphenated, if two lines in a row are hyphenated, or if a very loose line is immediately followed by a very tight line. The algorithm will then find the breakpoints that will minimize the sum of squares of the badness (including penalties) of the resulting lines. If the paragraph contains possible breakpoints, the number of situations that must be evaluated naively is . However, by using the method of dynamic programming, the complexity of the algorithm can be brought down to (see Big O notation). Further simplifications (for example, not testing extremely unlikely breakpoints such as a hyphenation in the first word of a paragraph, or very overfull lines) lead to an efficient algorithm whose running time is , where is the width of a line. A similar algorithm is used to determine the best way to break paragraphs across two pages, in order to avoid

^{[39]}

If no suitable line break can be found for a line, the system will try to hyphenate a word. The original version of TeX used a hyphenation algorithm based on a set of rules for the removal of prefixes and suffixes of words, and for deciding if it should insert a break between the two consonants in a pattern of the form

*en-cy-clo-pe-di-a*. This system based on subwords allows the definition of very general patterns (such as

_{2}i

_{1}a), with low indicative numbers (either odd or even), which can then be superseded by more specific patterns (such as

_{1}d

_{4}i

_{3}a) if necessary. These patterns find about 90% of the hyphens in the original dictionary; more importantly, they do not insert any spurious hyphen. In addition, a list of exceptions (words for which the patterns do not predict the correct hyphenation) are included with the Plain TeX format; additional ones can be specified by the user.

^{[41]}

^{[page needed]}

^{[42]}

### Metafont

Metafont, not strictly part of TeX, is a font description system which allows the designer to describe characters algorithmically. It uses Bézier curves in a fairly standard way to generate the actual characters to be displayed, but Knuth devotes substantial attention to the rasterizing problem on bitmapped displays. Another thesis, by John Hobby, further explores this problem of digitizing "brush trajectories". This term derives from the fact that Metafont describes characters as having been drawn by abstract brushes (and erasers). It is commonly believed that TeX is based on bitmap fonts but, in fact, these programs "know" nothing about the fonts that they are using other than their dimensions. It is the responsibility of the device driver to appropriately handle fonts of other types, including PostScript Type 1 and TrueType. Computer Modern (commonly known as "the TeX font") is freely available in Type 1 format, as are the AMS math fonts. Users of TeX systems that output directly to PDF, such as pdfTeX, XeTeX, or LuaTeX, generally never use Metafont output at all.

### Macro language

TeX documents are written and programmed using an unusual macro language. Broadly speaking, the running of this macro language involves expansion and execution stages which do not interact directly. Expansion includes both literal expansion of macro definitions as well as conditional branching, and execution involves such tasks as setting variables/registers and the actual typesetting process of adding glyphs to boxes.

The definition of a macro not only includes a list of commands but also the syntax of the call. It differs with most widely used

The TeX macro language has been used to write larger document production systems, most notably including LaTeX and ConTeXt.

## Development

The original source code for the current TeX software is written in

^{[45]}) and doubled every year until it was frozen at its current value of $327.68. Knuth has lost relatively little money as there have been very few bugs claimed. In addition, recipients have been known to frame their check as proof that they found a bug in TeX rather than cashing it.

^{[46]}

^{[47]}

Due to scammers finding scanned copies of his checks on the internet and using them to try to drain his bank account, Knuth no longer sends out real checks, but those who submit bug reports can get credit at The Bank of San Serriffe instead.^{[48]}

## Distributions and extensions

TeX is usually provided in the form of an easy-to-install bundle of TeX itself along with

Several document processing systems are based on TeX, notably

, the GNU documentation processing system. TeX has been the official typesetting package for the GNU operating system since 1984.Numerous extensions and companion programs for TeX exist, among them BibTeX for bibliographies (distributed with LaTeX); pdfTeX, a TeX-compatible engine which can directly produce PDF output (as well as continuing to support the original DVI output); XeTeX, a TeX-compatible engine that supports Unicode and OpenType; and LuaTeX, a Unicode-aware extension to TeX that includes a Lua runtime with extensive hooks into the underlying TeX routines and algorithms. Most TeX extensions are available for free from CTAN, the Comprehensive TeX Archive Network.

### Editors

There are a variety of editors designed to work with TeX:

- The TeXmacs text editor is a WYSIWYG-WYSIWYM scientific text editor, inspired by both TeX and Emacs. It uses Knuth's fonts and can generate TeX output.
- Overleaf is a partial-WYSIWYG, online editor that provides a cloud-based solution to TeX along with additional features in real-time collaborative editing.
- LyX is a WYSIWYM document processor which runs on a variety of platforms including:
- Linux,
- Microsoft Windows (newer versions require Windows 2000 or later)
- Apple Qtfront-end).

- TeXShop (for macOS), TeXworks (for Linux, macOS and Windows) and WinShell (for Windows) are similar tools and provide an integrated development environment (IDE) for working with LaTeX or TeX. For KDE/Qt, Kile provides such an IDE.
- Texmaker is the Pure Qt equivalent of Kile, with a user interface that is nearly the same as Kile's.
- TeXstudio is an open-source fork (2009) of Texmaker that offers a different approach to configurability and features. Free downloadable binaries are provided for Windows, Linux, macOS, OS/2, and FreeBSD.
- GNU Emacs has various built-in and third-party packages with support for TeX, the major one being AUCTeX.
- Visual Studio Code. A notable extension is LaTeX Workshop
- For Vim, possible plugins include Vim-LaTeX Suite,
^{[49]}Automatic TeX^{[50]}and TeX-9.^{[51]} - For Apache OpenOffice and LibreOffice, iMath and TexMaths extensions can provide mathematical TeX typesetting.
^{[52]}^{[53]} - For MediaWiki, the Math extension provides mathematical TeX typesetting, but the code needs to be surrounded by
`<math>`

tag.

### License

Donald Knuth has indicated several times^{[54]}^{[55]}^{[56]} that the source code of TeX has been placed into the "public domain", and he strongly encourages modifications or experimentations with this source code. However, since Knuth highly values the reproducibility of the output of all versions of TeX, any changed version must not be called TeX, or anything confusingly similar. To enforce this rule, any implementation of the system must pass a test suite called the TRIP test^{[57]} before being allowed to be called TeX. The question of license is somewhat confused by the statements included at the beginning of the TeX source code,^{[58]} which indicate that "all rights are reserved. Copying of this file is authorized only if ... you make absolutely no changes to your copy". This restriction should be interpreted as a prohibition to change the source code *as long as the file is called tex.web*. The copyright note at the beginning of tex.web (and mf.web) was changed in 2021 to explicitly state this. This interpretation is confirmed later in the source code when the TRIP test is mentioned ("If this program is changed, the resulting system should not be called 'TeX'").^{[59]} The American Mathematical Society tried in the early 1980s to claim a trademark for TeX. This was rejected because at the time "TEX" (all caps) was registered by Honeywell for the "Text EXecutive" text processing system.^{[citation needed]}

### XML publication

It is possible to use TeX for automatic generation of sophisticated layout for XML data. The differences in syntax between the two description languages can be overcome with the help of TeXML. In the context of XML publication, TeX can thus be considered an alternative to XSL-FO. TeX allowed scientific papers in mathematical disciplines to be reduced to relatively small files that could be rendered client-side, allowing fully typeset scientific papers to be exchanged over the early Internet and emerging World Wide Web, even when sending large files was difficult. This paved the way for the creation of repositories of scientific papers such as arXiv, through which papers could be 'published' without an intermediary publisher.^{[60]}

## Pronunciation and spelling

The name TeX is intended by its developer to be pronounced

*technē*), Greek for both "art" and "craft", which is also the root word of

*technical*. English speakers often pronounce it /tɛk/, like the first syllable of

*technical*. Knuth instructs that it be typeset with the "E" below the baseline and reduced spacing between the letters. This is done, as Knuth mentions in his

*TeXbook*, to distinguish TeX from other system names such as TEX, the Text EXecutive processor (developed by Honeywell Information Systems).

^{[62]}Fans like to proliferate names from the word "TeX"—such as

*TeXnician*(user of TeX software),

*TeXhacker*(TeX programmer),

*TeXmaster*(competent TeX programmer),

*TeXhax*, and

*TeXnique*.

^{[63]}

## Community

Notable entities in the TeX community include the TeX Users Group (TUG), which currently publishes

*digital typography relevant to TeX. The Deutschsprachige Anwendervereinigung TeX (DANTE) is a large user group in Germany. The TeX Users Group was founded in 1980 for educational and scientific purposes, provides an organization for those who have an interest in typography and font design, and are users of the TeX typesetting system invented by Knuth. The TeX Users Group represents the interests of TeX users worldwide. The TeX Users Group publishes the journal*

*TUGboat*three times per year;^{[64]}DANTE publishes*Die TeXnische Komödie*four times per year. Other user groups include DK-TUG in Denmark, GUTenberg in France, GuIT in Italy, NTG in the Netherlands and UK-TUG in the United Kingdom; the user groups jointly maintain a complete list.^{[65]}*
*

## Extensions

## See also

- Comparison of document markup languages
- Formula editor
- List of document markup languages
- MathJax - TeX on Web pages via JavaScript
- MathTime
- New Typesetting System – a TeX reimplementation (discontinued)
- PGF/TikZ
- PSTricks
- xdvi – a program for viewing .dvi files
- Help:Displaying a formula, for help displaying mathematical formulae in Wikipedia

## Notes

**^**Unregistered media type**^**Although*troff*still remains as the default formatter of the UNIX documentation.

## References

**^**"TeX Live - TeX Users Group".*tug.org*. Retrieved 25 April 2024.**^**"Per Bothner (attendee at TeX Project meetings) discusses authorship".Knuth definitely wrote most of the code himself, at least for the Metafont re-write, for which I have pe[r]sonal knowledge. However, some of his students (such as Michael Plass and John Hobby) did work on the algorithms used in TeX and Metafont.

**^**Yannis Haralambous.*Fonts & Encodings (Translated by P. Scott Horne)*. Beijing; Sebastopol, Calif: O'Reilly Media, 2007, pp. 235.**)****^**Knuth, Donald E. "Less brief biography".*Don Knuth's Home Page*. Archived from the original on 5 December 2016. Retrieved 9 January 2017.**^**Knuth, Donald E. "Commemorative lecture of the Kyoto Prize, 1996" (PDF). Kyoto Prize. Archived from the original (PDF) on 27 January 2018. Retrieved 18 August 2018.**^**Knuth, Donald Ervin,*TEXDR.AFT*, archived from the original on 12 January 2015**^**This article is based on material taken from TeX at the*Free On-line Dictionary of Computing*prior to 1 November 2008 and incorporated under the "relicensing" terms of the GFDL, version 1.3 or later.**^**Knuth & Plass 1981, p. 144.**^**Knuth, Donald E.*Knuth meets NTG members*, NTG: MAPS.**16**(1996), 38–49. Reprinted as*Questions and Answers, III*, chapter 33 of*Digital Typography*, p. 648.**^**Knuth, Donald E.*The New Versions of TeX and METAFONT*, TUGboat**10**(1989), 325–328;**11**(1990), 12. Reprinted as chapter 29 of*Digital Typography*.- ISBN 978-0-19-509686-6.
**^**"TeX 21 release". Retrieved 5 January 2022.- ^
^{a}^{b}"What is the future of TeX?".*The TeX FAQ*. 27 May 2018. Archived from the original on 28 April 2019. Retrieved 21 July 2019. **^**Knuth, Donald E.*The future of TeX and METAFONT*, NTG journal MAPS (1990), 489. Reprinted as chapter 30 of*Digital Typography*, p. 571.**^**"TeX Engine development".*The TeX FAQ*. 24 May 2018. Archived from the original on 28 April 2019. Retrieved 21 July 2019.- ^ )
**^**Beebe 2004, p. 10.**)****)****^**Jeffrey, Alan (1990), "Lists in TeX's Mouth" (PDF),*TUGboat*,**11**(2): 237–45**^**"CTAN: Package pdftex".*ctan.org*. Retrieved 21 July 2019.**^**Knuth 1984, p. 9.**^***Plain TeX*(source code), CTAN**^**"What are the AMS packages (amsmath, etc.)?".*The TeX FAQ*. 27 May 2018. Archived from the original on 28 April 2019. Retrieved 21 July 2019.**^**Knuth 1984, p. 127, Ch. 16: Typing Math Formulas.- ISBN 9780262691314
**)****^**Knuth, Donald E.*Typesetting Concrete Mathematics*, TUGboat**10**(1989), pp. 31–36, 342. Reprinted as chapter 18 of*Digital Typography*, pp. 367–378.**^**Vieth, Ulrik. "Math typesetting in TEX: The good, the bad, the ugly" (PDF). Archived from the original (PDF) on 20 January 2022.**^**"High-Quality Editing and Display of Mathematical Text in Office 2007".**^**"LineServices".**^**"Map" (PDF).*ntg.nl*.**^**Barnett, Michael P (1965),*Computer Typesetting: Experiments and Prospects*, Cambridge, MA: MIT Press**^**url=http://svn.tug.org/interviews/plass.html**^**Knuth & Plass 1981.**^**"Donald E. Knuth",*TUGboat*(interview),**21**, Advogato: 103–10, 2000, archived from the original on 22 January 2009, retrieved 26 December 2005**^**"4.1 fmt: Reformat paragraph text",*Core GNU utilities (GNU coreutils) manual*, GNU Project, 2016**^**Liang 1983, p. 3.**^**Liang 1983.**^**"Appendix H: Hyphenation",*The TeXbook*, pp. 449–55**^**Knuth, Donald E. List of updates to the TeX82 listing published in September 1982, available on CTAN.**^**Knuth, Donald E. Appendix to the*Errors of TeX*paper, available on CTAN, last modified in January 2003.**^**Knuth, Donald E. "Knuth: Frequently Asked Questions".*Stanford Computer Science*. Archived from the original on 6 March 2008. Retrieved 28 November 2019.- on 4 June 2006.
*Stanford Magazine*. Archived from the original **^**"History of TeX".*TeX Users Group*. Retrieved 28 November 2019.**^**Knuth, Donald E (2008). "Knuth: Recent News – Financial Fiasco".*Stanford Computer Science*. Archived from the original on 29 November 2019. Retrieved 29 November 2019.**^***Vim-LaTex*, SourceForge, archived from the original on 8 March 2024**^***Automatic TeX plugin*, Launch pad^{[permanent dead link]}**^***TeX-9*, Vim.org**^***TexMaths Homepage*, free.fr**^***iMath*, SourceForge**)****^**Knuth, Donald E (1986), "Computers and Typesettings" (PDF),*TUGboat*,**7**: 95–98**)****^**"Trip",*CTAN*(TeX) (source code)- ISBN 0-201-13437-3
**^**Open Source: Technology and Policy by Fadi P. Deek, James A. M. McHugh "Public domain", page 227 (2008)- arXiv:physics/0007040
**.** **^**Knuth, Donald E.*The TeXbook*, Ch. 1: The Name of the Game, p. 1.**^**Knuth, Donald E.*The TeX Logo in Various Fonts*, TUGboat**7**(1986), 101. Reprinted as chapter 6 of*Digital Typography*.**^**"The Jargon File—TeX". Retrieved 23 July 2016.**^**"The Communications of the TeX Users Group".*tug.org*. TeX Users Group. Retrieved 15 March 2019.**^**"All TeX User Groups".*tug.org*. TeX Users Group. Retrieved 17 November 2019.

**
**### Sources

- Beebe, Nelson HF (2004), "25 Years of TeX and METAFONT: Looking Back and Looking Forward" (PDF),
*TUGboat*,**25**: 7–30. - Knuth, Donald Ervin (1984),
*The TeXbook*,ISBN 0-201-13448-9. The source code of the book in TeX (and a needed set of macros [1]) is available online on CTAN. It is provided only as an example and its use to prepare a book like The TeXbook is not allowed. - ——— (1986),
*TeX: The Program*, Computers and Typesetting, vol. B, Reading,ISBN 0-201-13437-3. The full source code of TeX; also available on CTAN. Being written using literate programming, it contains plenty of human-readable documentation. - ——— (1999),
*Digital Typography*, Lecture notes, Center for the Study of Language and Information,ISBN 1-57586-010-4. - ———; Plass, Michael F (1981), "Breaking Paragraphs into Lines",
*Software: Practice and Experience*,**11**(11): 1119–84, ). - ———,
*TeX*(source code), archived from the original (WEB) on 27 September 2011 contains extensive documentation about the algorithms used in TeX. - ISBN 0-201-52983-1.
- Liang, Franklin Mark (August 1983),
*Word Hy-phen-a-tion by Com-put-er*(PhD thesis), Department of Computer Science, Stanford University. - Salomon, David (1995),
*The Advanced TeXbook*, Springer, . - Spivak, MD (1990),
*The Joy of TeX*(reference) (2nd ed.), American Mathematical Society, on AMS-TeX. - Vulis, Michael (1992),
*Modern TeX and Its Applications*, CRC Press,ISBN 0-8493-4431-X.

## External links

- TeX Users' Group
*TeX*(questions and answers), StackExchange.- Eijkhout, Victor.
*TeX by Topic*Archived 25 February 2021 at the Wayback Machine *TeX for the Impatient*- Donald Knuth discusses developing the software for TEX at Xerox PARC 2/21/1980 https://archive.org/details/xerox-parc-tapes-v49