TeX
Developed by	Donald Knuth
Latest release	3. A software developer is a person or organization concerned with facets of the software development process wider than design and coding a somewhat broader scope of Donald Ervin Knuth (kəˈnuːθ (born 10 January 1938) is a renowned computer scientist and Professor Emeritus of the Art of Computer A software release is the distribution whether public or private of an initial or new and upgraded version of a Computer software product 1415926 / March 2008
OS	Cross-platform
Genre	Typesetting
License	Permissive
Website	http://www.tug.org/

TeX (pronounced /ˈtɛx/, as in Greek, often /ˈtɛk/ in English; written with a lowercase 'e' in imitation of the logo) is a typesetting system created by Donald Knuth. An operating system (commonly abbreviated OS and O/S) is the software component of a Computer system that is responsible for the management and coordination In computing cross-platform (also known as multi-platform) is a term used to refer to Computer software or computing methods and concepts that are implemented Computer software can be organized into categories based on common function type or field of use Typesetting involves the presentation of textual material in graphic form on Paper or some other medium. A software license (or software licence in commonwealth usage is a Legal instrument governing the usage or redistribution of copyright protected software A website (alternatively web site or Web site, a back-construction from the Proper noun World Wide Web) is a collection of Web pages Modern Greek (el Νέα Ελληνικά or el Νεοελληνική lit English is a West Germanic language originating in England and is the First language for most people in the United Kingdom, the United States Typesetting involves the presentation of textual material in graphic form on Paper or some other medium. Donald Ervin Knuth (kəˈnuːθ (born 10 January 1938) is a renowned computer scientist and Professor Emeritus of the Art of Computer Together with the METAFONT language for font description and the Computer Modern typefaces, it was designed with two main goals in mind: to allow anybody to produce high-quality books using a reasonable amount of effort, and to provide a system that would give the exact same results on all computers, now and in the future. Metafont is a Programming language used to define vector fonts. Computer Modern is the family of Typefaces used by default by the typesetting program TeX. In Typography, a typeface is a set of one or more Fonts designed with stylistic unity each comprising a coordinated set of Glyphs A typeface usually comprises Within the typesetting system, its name is formatted as TeX.

TeX is considered by many to be the best way to typeset complex mathematical formulae. ^[1] TeX is popular in academia, especially in the mathematics and physics communities. Mathematics is the body of Knowledge and Academic discipline that studies such concepts as Quantity, Structure, Space and Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. In biological terms a community is a group of interacting Organisms sharing an environment. It has largely displaced Unix troff, the other favored formatter, in many Unix installations, which use both for different purposes. Unix (officially trademarked as UNIX, sometimes also written as Unix with Small caps) is a computer See also Trough. TROFF may also refer to a command in the BASIC programming language. It is now also being used for many other typesetting tasks, especially in the form of LaTeX and other template packages. LaTeX (ˈleɪtɛ

The widely-used MIME Type for TeX is application/x-tex. Multipurpose Internet Mail Extensions ( MIME) is an Internet standard that extends the format of e-mail to support text in Character TeX is free software. Free software or software libre is Software that can be used studied and modified without restriction and which can be copied and redistributed in modified or unmodified

Contents 1 History 2 The typesetting system 2.1 How TeX is run 2.2 Mathematical example 3 Novel aspects of TeX 3.1 Mathematical spacing 3.2 Hyphenation and justification 3.3 METAFONT 3.4 TeX macro language 4 Development 4.1 Packages 4.2 Editors 4.3 License 5 Use of TeX 6 Pronouncing and writing TeX 7 Community 8 See also 9 References 10 Notes 11 External links

History

When the first volume of Knuth's The Art of Computer Programming was published in 1969, it was typeset using hot metal type set by a Monotype Corporation linecaster, a hot metal typesetting machine from the 19th century which produced a “good classic style” appreciated by Knuth. The Art of Computer Programming is a comprehensive Monograph written by Donald Knuth that covers many kinds of Programming Algorithms Year 1969 ( MCMLXIX) was a Common year starting on Wednesday (link will display full calendar of the Gregorian calendar. Monotype Imaging Inc is a Typesetting and Typeface design company ( Type foundry) responsible for many developments in Printing technology Hot metal typesetting (also called hot lead typesetting or simply hot metal) is a term used to encompass a range of different 19th century technologies to create The 19th century of the Common Era began on January 1, 1801 and ended on December 31, 1900, according to the Gregorian calendar When the second edition of the second volume was published, in 1976, the whole book had to be typeset again because the Monotype technology had been largely replaced by photographic techniques, and the original fonts were not available any more. Year 1976 ( MCMLXXVI) was a Leap year starting on Thursday (link will display full calendar of the Gregorian calendar. ^[2] However, when Knuth received the galley proofs of the new book on 30 March 1977, he found them awful. Galleys redirects here For other uses see Galley (disambiguation. Events 240 BC - 1st recorded Perihelion passage of Halley's Comet. Also 1977 (album by Ash. Year 1977 ( MCMLXXVII) was a Common year starting on Saturday (link displays ^[3] Around that time, Knuth saw for the first time the output of a high-quality digital typesetting system, and became interested in digital typography. The disappointing galley proofs gave him the final motivation to solve the problem at hand once and for all by designing his own typesetting system. On May 13, 1977, he wrote a memo to himself describing the basic features of TeX. Events 1497 - Pope Alexander VI excommunicates Girolamo Savonarola. Also 1977 (album by Ash. Year 1977 ( MCMLXXVII) was a Common year starting on Saturday (link displays ^[4]

He planned to finish it on his sabbatical in 1978, but as it happened the language was frozen only in 1989, more than ten years later. A sabbatical (from the Latin sabbaticus, from the Greek sabbatikos, from Hebrew shabbathon, i Year 1978 ( MCMLXXVIII) was a Common year starting on Sunday (link displays the 1978 Gregorian calendar) Year 1989 ( MCMLXXXIX) was a Common year starting on Sunday (link displays 1989 Gregorian calendar) Guy Steele happened to be at Stanford during the summer of 1978, when Knuth was developing his first version of TeX. Guy Lewis Steele Jr, (ˈstiːl as in steel) also known as "The Great Quux" and GLS (glis is an American Computer scientist Leland Stanford Junior University, commonly known as Stanford University or simply Stanford, is a private Research university located in Year 1978 ( MCMLXXVIII) was a Common year starting on Sunday (link displays the 1978 Gregorian calendar) When Steele returned to MIT that fall, he rewrote TeX's I/O to run under the ITS operating system. ITS, the Incompatible Timesharing System (named in comparison with the Compatible Time-Sharing System also in use at MIT was an early revolutionary and influential The first version of TeX was written in the SAIL programming language to run on a PDP-10 under Stanford's WAITS operating system. SAIL, the Stanford Artificial Intelligence Language, was developed by Dan Swinehart and Bob Sproull of the Stanford AI Lab in 1970 The PDP-10 was a Mainframe computer manufactured by Digital Equipment Corporation (DEC from the late 1960s on the name stands for "Programmed Data Processor WAITS was a heavily-modified variant of Digital Equipment Corporation 's Monitor Operating system (later renamed to and better known as TOPS-10) for the For later versions of TeX, Knuth invented the concept of literate programming, a way of producing compilable source code and high quality cross-linked documentation (typeset in TeX, of course) from the same original file. Literate programming is a philosophy of Computer programming based on the premise that a Computer program should be written similar to Literature, with In Computer science, source code (commonly just source or code) is any sequence of statements or declarations written in some Human-readable The language used is called WEB and produces programs in Pascal. WEB is a Computer programming system created by Donald E Knuth as the first implementation of what he called " Literate programming " the Pascal is an influential imperative and procedural Programming language, designed in 1968/9 and published in 1970 by Niklaus Wirth as a small

A new version of TeX, rewritten from scratch and called TeX82, was published in 1982. Year 1982 ( MCMLXXXII) was a Common year starting on Friday (link displays the 1982 Gregorian calendar) Among other changes, the original hyphenation algorithm was replaced by a new algorithm written by Frank Liang. A hyphen ( -) is a Punctuation mark It is used for both Words to join and to separate Syllables It is often confused with the dashes TeX82 also uses fixed-point arithmetic instead of floating-point, to ensure reproducibility of the results across different computer hardware,^[5] and includes a real, Turing-complete programming language, following intense lobbying by Guy Steele. In Computing, a fixed-point number representation is a Real data type for a number that has a fixed number of digits after (and sometimes also before the In Computing, floating point describes a system for numerical representation in which a string of digits (or Bits represents a Real number. In computability theory, several closely-related terms are used to describe the "computational power" of a computational system (such as an Abstract machine or Guy Lewis Steele Jr, (ˈstiːl as in steel) also known as "The Great Quux" and GLS (glis is an American Computer scientist ^[6]

In 1989, Donald Knuth released new versions of TeX and METAFONT. Year 1989 ( MCMLXXXIX) was a Common year starting on Sunday (link displays 1989 Gregorian calendar) Metafont is a Programming language used to define vector fonts. ^[7] Despite his desire to keep the program stable, Knuth realised that 128 different characters for the text input were not enough to accommodate foreign languages; the main change in version 3. 0 of TeX is thus the ability to work with 8-bits inputs, allowing 256 different characters in the text input.

Since version 3, TeX has used an idiosyncratic version numbering system, where updates have been indicated by adding an extra digit at the end of the decimal, so that the version number asymptotically approaches π. Software versioning is the process of assigning either unique version names or unique version numbers to unique states of Computer software. An asymptote of a real-valued function y=f(x is a curve which describes the behavior of f as either x or y goes to infinity IMPORTANT NOTICE Please note that Wikipedia is not a database to store the millions of digits of π please refrain from adding those to Wikipedia as it could cause technical problems This is a reflection of the fact that TeX is now very stable, and only minor updates are anticipated. The current version of TeX is 3. 1415926; it was last updated in March 2008. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common The design has been frozen after version 3. 0, and no new feature or fundamental change will be added after that, so that all newer versions shall contain only bug fixes. A software bug (or just “bug” is an error flaw mistake Failure, fault or “undocumented feature” in a Computer program that prevents it 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. ^[8] Likewise, versions of METAFONT after 2. 0 asymptotically approach e, and a similar change will be applied after Knuth's death. The Mathematical constant e is the unique Real number such that the function e x has the same value as the slope of the tangent line

However, since the source code of TeX is essentially in the public domain (see below), other programmers are allowed (and explicitly encouraged) to improve the system, but are required to use another name to distribute the modified TeX, meaning that the source code can still evolve. The public domain is a range of abstract materials &ndash commonly referred to as Intellectual property &ndash which are not owned or controlled by anyone For example, the Omega project was developed after 1991, primarily to enhance TeX's multilingual typesetting abilities. Omega is an extension of the TeX typesetting system that uses the Basic Multilingual Plane of Unicode. Year 1991 ( MCMXCI) was a Common year starting on Tuesday (link will display full calendar of the Gregorian Calendar. Donald Knuth himself created “unofficial” modified versions, such as TeX-XeT, which allows a user to mix texts written in left-to-right and right-to-left writing systems in the same document. A writing system is a type of Symbolic system used to represent elements or statements expressible in Language. ^[9]

The typesetting system

TeX commands commonly start with a backslash and are grouped with curly braces. The backslash ( \) is a typographical mark ( Glyph) used chiefly in Computing. Brackets are Punctuation marks used in pairs to set apart or interject text within other text However, almost all of TeX's syntactic properties can be changed on the fly which makes TeX input hard to parse by anything but TeX itself. TeX is a macro- and token-based language: many commands, including most user-defined ones, are expanded on the fly until only unexpandable tokens remain which get executed. A macro (from the Greek 'μάκρο' for long or far in Computer science is a rule or Pattern that specifies how a certain input sequence (often a sequence In Computer science, lexical analysis is the process of converting a sequence of characters into a sequence of tokens Expansion itself is practically side-effect free. Tail recursion of macros takes no memory, and if-then-else constructs are available. In Computer science, tail recursion (or tail-end recursion) is a special case of recursion in which the last operation of the function is a recursive call This makes TeX a Turing-complete language even at expansion level. In computability theory, several closely-related terms are used to describe the "computational power" of a computational system (such as an Abstract machine or

The system can be divided into four levels: in the first, characters are read from the input file and assigned a category code (sometimes called “catcode”, for short). Combinations of a backslash (really: any character of category zero) followed by letters (characters of category 11) or a single other character are replaced by a control sequence token. In this sense this stage is like lexical analysis, although it does not form numbers from digits. In the next stage, expandable control sequences (such as conditionals or defined macros) are replaced by their replacement text. The input for the third stage is then a stream of characters (including ones with special meaning) and unexpandable control sequences (typically assignments and visual commands). Here characters get assembled into a paragraph. TeX's paragraph breaking algorithm works by optimizing breakpoints over the whole paragraph. The fourth stage breaks the vertical list of lines and other material into pages.

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 DVI file (“DeVice Independent”) containing the final locations of all characters. DVI stands for device independent There also is an article about Device independent. This dvi file can be printed directly given an appropriate printer driver, or it can be converted to other formats. Nowadays, PDFTeX is often used which bypasses DVI generation altogether. pdfTeX is an extension of Knuth 's typesetting program TeX, and was originally written and developed into a publicly usable product by Hàn Thế Thành as a

The base TeX system understands about 300 commands, called primitives. ^[10] However, these low-level commands are rarely used directly by users, and most functionality is provided by format files (predumped memory images of TeX after large macro collections have been loaded). Knuth's original default format, which adds about 600 commands, is Plain TeX (available from CTAN). The most widely used format is LaTeX, originally developed by Leslie Lamport, which incorporates document styles for books, letters, slides, etc, and adds support for referencing and automatic numbering of sections and equations. LaTeX (ˈleɪtɛ Dr Leslie Lamport (born February 7, 1941 in New York City) is an American computer scientist. Another widely used format, AMS-TeX, is produced by the American Mathematical Society, and provides many more user-friendly commands, which can be altered by journals to fit with their house style. AMS-LaTeX is a collection of LaTeX document classes and packages developed for the American Mathematical Society (AMS The American Mathematical Society (AMS is an association of professional Mathematicians dedicated to the interests of mathematical research and scholarship which Most of the features of AMS-TeX can be used in LaTeX by using the AMS “packages”. This is then referred to as AMS-LaTeX. AMS-LaTeX is a collection of LaTeX document classes and packages developed for the American Mathematical Society (AMS Other formats include ConTeXt, used primarily for desktop publishing and written mostly by Hans Hagen at Pragma. ConTEXT is a closed-source Freeware Text editor for Microsoft Windows, aimed at software developers Hans Hagen is the developer of ConTeXt, a freely available macro package for the TeX Typesetting system and the owner of PRAGMA Advanced Document

How TeX is run

A sample Hello world program in plain TeX is:

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

This might be in a file myfile. A "Hello World" program is a Computer program that prints out "Hello world!" on a Display device. tex, as . tex is a common file extension for plain TeX files. A filename extension is a suffix to the name of a Computer file applied to indicate the encoding convention ( File format) of its contents

By default, everything that follows a percent sign on a line is a comment, ignored by TeX. Running TeX on this file (for example, by typing tex myfile. tex in a command line interpreter, or by calling it from a graphical user interface) will create an output file called myfile. dvi, representing the content of the page in a device independent format (DVI). DVI stands for device independent There also is an article about Device independent. The results can either be printed directly from a DVI viewer or converted to a more common format such as PostScript using the dvips program. PostScript ( PS) is a dynamically typed concatenative Programming language created by John Warnock and Charles Geschke in 1982 In Computing, dvips is the most widely used program for converting the output of the{\mathrm{T\!_{\displaystyle E} \! X}}\mathrm{T\!_{\displaystyle This was because TeX natively uses bitmap fonts, which are only designed to display well at one particular size, whereas PostScript typically uses scalable Type 1 fonts. This article is about font technology For information about the typographic appearance of individual font sets see Typefaces A computer font (or PostScript ( PS) is a dynamically typed concatenative Programming language created by John Warnock and Charles Geschke in 1982 It is now possible to make dvips output scalable fonts with a bit of tweaking (newer versions of Ghostscript support it). TeX variants such as PDFTeX produce PDF files directly. pdfTeX is an extension of Knuth 's typesetting program TeX, and was originally written and developed into a publicly usable product by Hàn Thế Thành as a

Mathematical example

TeX provides a text syntax for mathematical formulae. For example, the well-known quadratic formula, would appear as:

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

and the output would resemble:

The quadratic formula is

Notice how the formula is printed in a way a person would write by hand, or typeset the equation. In Mathematics, a quadratic equation is a Polynomial Equation of the second degree. In a document, entering mathematics mode is done by starting with a $, then entering a formula in TeX semantics and closing again with another $. Knuth explained in a 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. ^[11] Display mathematics (mathematics presented centered on a new line) is similar but uses $$ instead of $. For example, the above with the quadratic formula in display math:

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

renders as

The quadratic formula is

Novel aspects of TeX

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 a number of 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 TeX was the high-quality typesetting of his book The Art of Computer Programming, Knuth gave a lot of attention to the choice of proper spacing rules for mathematical formulae. He took three bodies of work that he considered as standards of excellence for mathematical typography: the books typeset by Addison-Wesley, the publisher of The Art of Computer Programming, in particular the work done by Hans Wolf; editions of the mathematical journal Acta Mathematica dating from around 1910; and a copy of Indagationes Mathematicae, a Dutch mathematics journal. Addison-Wesley is a Book publishing imprint of Pearson PLC, best known for computer books Acta Mathematica is a journal publishing original research papers in all fields of Mathematics. Year 1910 ( MCMX) was a Common year starting on Saturday (link will display calendar of the Gregorian calendar (or a Common year starting The Netherlands ( Dutch:, ˈnedərlɑnt is the European part of the Kingdom of the Netherlands, which consists of the Netherlands the Netherlands Knuth looked closely at these examples to derive a set of spacing rules for TeX. ^[12] 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 frozen, but when other fonts, such as AMS Euler, were used by Knuth for the first time, new spacing parameters had to be defined. Computer Modern is the family of Typefaces used by default by the typesetting program TeX. AMS Euler is an Upright Cursive Typeface, commissioned by the American Mathematical Society (AMS and designed and created by Hermann ^[13]

Hyphenation and justification

In comparison with manual typesetting, the problem of justification is easy to solve with a digital system such as TeX, which, provided that good points for line breaking have been defined, can automatically spread the spaces between words to fill in the line. In Typesetting, justification (can also be referred to as 'full justification' is the Typographic alignment setting of text or Images within The problem is thus to find the set of breakpoints that will give the most pleasing result. Many line breaking algorithms use a 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. ^[14] 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 considers 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 n possible breakpoints, the number of situations that must be evaluated naively is 2ⁿ. However, by using the method of dynamic programming, the complexity of the algorithm can be brought down to O(n²) (see Big O notation). In Mathematics and Computer science, dynamic programming is a method of solving problems exhibiting the properties of Overlapping subproblems and In mathematics big O notation (so called because it uses the symbol O) describes the limiting behavior of a function for very small or very large arguments Further simplifications (for example, not testing extremely unlikely breakpoints such as a hyphenation in the first word of a paragraph) lead to an efficient algorithm whose running time is almost always order of n. However, in general, a thesis by Michael Plass shows how the page breaking problem can be NP-complete because of the added complication of placing figures. In Computational complexity theory, the Complexity class NP-complete (abbreviated NP-C or NPC) is a class of problems having two properties ^[15] A similar algorithm is used to determine the best way to break paragraphs across two pages, in order to avoid widows or orphans (lines that appear alone on a page while the rest of the paragraph is on the following or preceding page). In Typesetting, a widow is the final line of a paragraph if it falls at the top of the following page column of text separated from the remainder of the paragraph on the In Typesetting, a widow is the final line of a paragraph if it falls at the top of the following page column of text separated from the remainder of the paragraph on the

TeX's line breaking algorithm has been adopted by several other programs, such as Adobe InDesign a desktop publishing application^[16], and the GNU fmt Unix command line utility. Adobe InDesign is a Desktop publishing (DTP software application produced by Adobe Systems. Desktop publishing (also known as DTP) combines a Personal computer and WYSIWYG page layout Software to create Publication Documents Application software is a subclass of Computer software that employs the capabilities of a computer directly and thoroughly to a task that the user wishes to perform GNU ( pronounced) is a computer Operating system composed entirely of Free software. The fmt command in Unix is used to format human language text Unix (officially trademarked as UNIX, sometimes also written as Unix with Small caps) is a computer ^[17]

If no suitable line break can be found for a line, the system will try to hyphenate a word. A hyphen ( -) is a Punctuation mark It is used for both Words to join and to separate Syllables It is often confused with the dashes 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 vowel–consonant–consonant–vowel (which is possible most of the time). A hyphenation algorithm is a set of rules (especially one codified for implemention in a computer program that decides at which points a word can be broken over two lines with a Hyphen In Phonetics, a vowel is a Sound in spoken Language, such as English ah! or oh!, pronounced with an open Vocal tract In Articulatory phonetics, a consonant is a Speech sound that is articulated with complete or partial closure of the upper Vocal tract, the upper vocal In Articulatory phonetics, a consonant is a Speech sound that is articulated with complete or partial closure of the upper Vocal tract, the upper vocal In Phonetics, a vowel is a Sound in spoken Language, such as English ah! or oh!, pronounced with an open Vocal tract ^[18] TeX82 uses a new hyphenation algorithm, designed by Frank Liang in 1983, to assign priorities to breakpoints in letter groups. Year 1983 ( MCMLXXXIII) was a Common year starting on Saturday (link displays the 1983 Gregorian calendar) A list of hyphenation patterns is first generated automatically from a corpus of hyphenated words (a list of 50,000 words). If TeX must find the acceptable hyphenation positions in the word encyclopedia, for example, it will consider all the subwords of the extended word . encyclopedia. , where . is a special marker to indicate the beginning or end of the word. The list of subwords include all the subwords of length 1 (. , e, n, c, y, etc), of length 2 (. e, en, nc, etc), etc, up to the subword of length 14, which is the word itself, including the markers. TeX will then look into its list of hyphenation patterns, and find subwords for which it has calculated the desirability of hyphenation at each position. In the case of our word, 11 such patterns can be matched, namely ₁c₄l₄, ₁cy, ₁d₄i₃a, ₄edi, e₃dia, ₂i₁a, ope₅d, ₂p₂ed, ₃pedi, pedia₄, y₁c. For each position in the word, TeX will calculate the maximum value obtained among all matching pattern, yielding en₁cy₁c₄l₄o₃p₄e₅d₄i₃a₄. Finally, the acceptable positions are those indicated by an odd number, yielding the acceptable hyphenations en-cy-clo-pe-di-a. In Mathematics, the parity of an object states whether it is even or odd This system based on subwords allows the definition of very general patterns (such as ₂i₁a), with low indicative numbers (either odd or even), which can then be superseded by more specific patterns (such as ₁d₄i₃a) 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. ^[19][20]

METAFONT

Main article: METAFONT

METAFONT, not strictly part of TeX, is a font description system which allows the designer to describe characters algorithmically. Metafont is a Programming language used to define vector fonts. It uses Bezier curves in a fairly standard way to generate the actual characters to be displayed, but Knuth devotes lots of attention to the rasterizing problem on bitmapped displays. In the mathematical field of Numerical analysis, a Bézier curve is a Parametric curve important in Computer graphics and related fields Font rasterization is the process of converting text from a vector description (as found in scalable fonts such as TrueType fonts to a raster or Bitmap In Computer graphics, a raster graphics image or bitmap, is a Data structure representing a generally rectangular grid of Pixels 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 possible to use TeX and LaTeX without METAFONT. Adobe PostScript (“Type 1”) fonts may be used instead. (La)TeX expects fonts to be supplied as bitmaps at specific point sizes, while PostScript is a vector (outline) description scalable over a wide range, so this does introduce some minor complications. Nonetheless, with the help of some prewritten packages, (La)TeX can be made to use PostScript fonts. Further note that “Type 1” or “T1” can refer in documentation to two very different things: the TeX T1 character encoding scheme to map byte values to glyphs, and Adobe PostScript fonts.

TeX macro language

TeX provides an unusual macro language; the definition of a macro not only includes a list of commands but also the syntax of the call. Macros are completely integrated with a full-scale interpreted compile-time language that also guides processing.

TeX's macro level of operation is lexical, but it is a built-in facility of TeX, that make use of syntax interpretation. Comparing with most widely used lexical preprocessors like M4, it differs slightly, as the body of a macro gets tokenized at definition time, that is, it is not completely raw text. In Computer science, a preprocessor is a program that processes its input data to produce output that is used as input to another program m4 is a General purpose macro processor designed by Brian Kernighan and Dennis Ritchie. Except for a few very special cases, this gives the same behaviour.

The TeX macro language has been successfully used to extend TeX to, for instance, LaTeX. LaTeX (ˈleɪtɛ

Development

The original source code for the current TeX software is written in WEB, a mixture of documentation written in TeX and a quite restricted Pascal subset in order to ensure portability. WEB is a Computer programming system created by Donald E Knuth as the first implementation of what he called " Literate programming " the Pascal is an influential imperative and procedural Programming language, designed in 1968/9 and published in 1970 by Niklaus Wirth as a small For example, TeX does all of its dynamic allocation itself from fixed-size arrays and uses only fixed-point arithmetic for its internal calculations. In Computing, a fixed-point number representation is a Real data type for a number that has a fixed number of digits after (and sometimes also before the As a result, TeX has been ported to almost all operating systems, usually by using the web2c program to convert the source code into C instead of directly compiling the Pascal code. An operating system (commonly abbreviated OS and O/S) is the software component of a Computer system that is responsible for the management and coordination tags please moot on the talk page first! --> In Computing, C is a general-purpose cross-platform block structured

Knuth has kept a very detailed log of all the bugs he has corrected and changes he has made in the program since 1982; as of 2005, the list contains 419 entries, not including the version modification that should be done after his death as the final change in TeX. Year 1982 ( MCMLXXXII) was a Common year starting on Friday (link displays the 1982 Gregorian calendar) Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar. ^[21][22] Donald Knuth offers monetary awards to people who find and report a bug in TeX. In the preface of each of his books and on his website computer scientist Donald Knuth offers to cheerfully pay a reward of $2 A software bug (or just “bug” is an error flaw mistake Failure, fault or “undocumented feature” in a Computer program that prevents it The award per bug started at $2. 56 (one "hexadecimal dollar"^[23]) and doubled every year until it was frozen at its current value of $327. 68. This has not made Knuth poor, however, as there have been very few bugs claimed. In addition, people have been known to frame a check proving they found a bug in TeX instead of cashing it. ^[24][25]

Packages

TeX is usually provided in the form of an easy-to-install bundle of TeX itself along with METAFONT and all the necessary fonts, documents formats, and utilities needed to use the typesetting system. Metafont is a Programming language used to define vector fonts. On UNIX-compatible systems, including Linux and Mac OS X, TeX is distributed in the form of the teTeX distribution and more recently the TeX Live distribution. Unix (officially trademarked as UNIX, sometimes also written as Unix with Small caps) is a computer Linux (commonly pronounced ˈlɪnəks Mac OS X (mæk oʊ ɛs tɛn is a line of computer Operating systems developed marketed and sold by Apple Inc, the latest of which is pre-loaded on all currently teTeX is a TeX distribution for Unix-like systems As of May 2006 teTeX is no longer actively maintained and its former maintainer Thomas Esser TeX Live is a TeX distribution which is advised as the replacement of its no-longer supported counterpart teTeX. On Microsoft Windows, there is the MiKTeX distribution (enhanced by ProTeX ) and the fpTeX distribution. Microsoft Windows is a series of Software Operating systems and Graphical user interfaces produced by Microsoft. MiKTeX is a TeX / LaTeX distribution for Microsoft Windows that is developed by Christian Schenk

Several document processing systems are based on TeX, notably jadeTeX, which uses TeX as a backend for printing from James Clark's DSSSL Engine, the Arbortext publishing system, and Texinfo, the GNU documentation processing system. James Clark, ( February 23 1964) is the author of groff and expat and has done much work with Open-source software and XML Arbortext is an XML -based publishing system available from PTC. Texinfo is a typesetting syntax used for generating documentation in both on-line and printed form (creating filetypes as dvi html pdf etc GNU ( pronounced) is a computer Operating system composed entirely of Free software. TeX has been the official typesetting package for the GNU operating system since 1984. GNU ( pronounced) is a computer Operating system composed entirely of Free software.

XeTeX is a new TeX engine that supports Unicode. XeTeX (ˈziːtɛx or /ˈziːtɛχ/ though English lacks /x/ or /χ/ is a TeX typesetting engine using Unicode and supporting modern font technologies In Computing, Unicode is an Industry standard allowing Computers to consistently represent and manipulate text expressed in most of the world's Originally making use of advanced Mac OS X-specific font technologies, it now supports OpenType and is available on Linux and Microsoft Windows. Mac OS X (mæk oʊ ɛs tɛn is a line of computer Operating systems developed marketed and sold by Apple Inc, the latest of which is pre-loaded on all currently OpenType is a scalable format for Computer fonts initially developed by Microsoft, later joined by Adobe Systems.

Numerous extensions and companion programs for TeX exist, among them BibTeX for bibliographies (distributed with LaTeX), pdfTeX, which bypasses dvi and produces output in Adobe Systems' Portable Document Format, and Omega, which allows TeX to use the Unicode character set. BibTeX is a tool for formatting lists of references. The BibTeX tool is typically used together with the LaTeX document preparation system pdfTeX is an extension of Knuth 's typesetting program TeX, and was originally written and developed into a publicly usable product by Hàn Thế Thành as a Adobe Systems Incorporated (pronounced a-DOE-bee əˈdoʊbiː ( is an American Computer software company headquartered in San Jose California Omega is an extension of the TeX typesetting system that uses the Basic Multilingual Plane of Unicode. In Computing, Unicode is an Industry standard allowing Computers to consistently represent and manipulate text expressed in most of the world's Most TeX extensions are available for free from CTAN, the Comprehensive TeX Archive Network. CTAN is an Acronym for the Comprehensive TeX Archive Network It is the authoritative place where TeX related material and Software can be

Editors

The TeXmacs text editor is a WYSIWYG scientific text editor that is intended to be compatible with TeX and Emacs. GNU TeXmacs is a free scientific Word processor component of the GNU project which was "inspired" by both TeX and GNU Emacs WYSIWYG (ˈwɪziwɪg or /ˈwɪzɪwɪg/ is an Acronym for W hat Y ou S ee I s W hat Y ou G Emacs is a class of feature-rich Text editors usually characterized by their extensibility It uses Knuth's fonts, and can generate TeX output.

LyX is a “What You See is What You Mean” document processor which runs on a variety of platforms including Linux, Windows (newer versions require Windows 2000 or later) or Mac OS X (using a non-native Qt front-end). Qt (pronounced "cute" by its creators is a Cross-platform application development framework widely used for the development of GUI programs (in which

TeXShop for Mac OS X, and WinShell for Windows are similar tools and provide integrated development environment (IDE) for working with LaTeX or TeX. TeXShop is a free TeX editor and previewer for Mac OS X. It is licensed under the GNU GPL. Mac OS X (mæk oʊ ɛs tɛn is a line of computer Operating systems developed marketed and sold by Apple Inc, the latest of which is pre-loaded on all currently WinShell is a freeware closed-source multilingual Integrated development environment (IDE for LaTeX and TeX for Windows developed by Ingo Microsoft Windows is a series of Software Operating systems and Graphical user interfaces produced by Microsoft. For KDE, Kile provides such an IDE. KDE ( K Desktop Environment) (ˌkeɪdiːˈiː is a Free software project which aims to be a powerful system for an easy-to-use Desktop environment. For the baseball pitcher see Darryl Kile. For the radio station see KILE.

GNU Emacs has various built-in and third party packages with support for TeX, the major one being AUCTeX. Emacs is a class of feature-rich Text editors usually characterized by their extensibility AUCTEX is an extensible package for writing and formatting TeX files in GNU Emacs and XEmacs. For Vim there is the Vim-LaTeX Suite. Vim is a Text editor first released by Bram Moolenaar in 1991 for the Amiga computer

License

Donald Knuth has indicated several times^[26][27] 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 the code is still copyrighted, it is technically free/open-source software but is not in the public domain in the legal sense. Free software or software libre is Software that can be used studied and modified without restriction and which can be copied and redistributed in modified or unmodified Open source software (OSS began as a marketing campaign for Free software. The public domain is a range of abstract materials &ndash commonly referred to as Intellectual property &ndash which are not owned or controlled by anyone In particular, since Knuth highly values the reproducibility of the output of all versions of TeX, any changed version must not be called T_EX, TeX, or anything confusingly similar. To enforce this rule, any implementation of the system must pass a test suite called the TRIP test (available on CTAN) 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^[28], which indicate that “all rights are reserved. Copying of this file is authorized only if (. . . ) you make absolutely no changes to your copy”. However, this restriction should be interpreted as a prohibition to change the source code as long as the file is called tex. web. 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’”).

The American Mathematical Society has also claimed a trademark for TeX, which was rejected, because at the time this was tried (early 1980s), “TEX” (all caps) was registered by Honeywell for the “Text EXecutive” text processing system. The American Mathematical Society (AMS is an association of professional Mathematicians dedicated to the interests of mathematical research and scholarship which A trademark or trade mark, represented by the symbols ™ and ®, or mark is a distinctive sign or indicator used by an individual Honeywell ( is a major American multinational conglomerate company that produces a variety of consumer products engineering services and aerospace systems ^[29]

Use of TeX

In several technical fields, in particular computer science, mathematics 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. Addison-Wesley is a Book publishing imprint of Pearson PLC, best known for computer books Cambridge University Press (known colloquially as CUP is a Publisher given a Royal Charter by Henry VIII in 1534 Elsevier, the world's largest Publisher of Medical and Scientific literature, forms part of the Reed Elsevier group Springer Science+Business Media or Springer (ˈʃpʁɪŋɐ is a worldwide Publishing company based in Germany, which publishes textbooks academic Numerous journals in these fields are produced using TeX or LaTeX, allowing authors to submit their raw manuscript written in TeX. ^[30]

While many publications in other fields, including dictionaries and legal publications, have been produced using TeX, it has not been as successful as in more technical fields, in particular because TeX was primarily designed for 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 publishers would design versions tailored to their needs. While such extensions have been created (including some by Knuth himself^[9]), most people have extended TeX only using macros and it has remained a system associated with technical typesetting. ^[31][32]

Pronouncing and writing TeX

The name TeX is intended to be pronounced /ˈtɛx/. The X is meant to represent the Greek letter χ (chi). The Greek alphabet (Ελληνικό αλφάβητο is a set of twenty-four letters that has been used to write the Greek language since the late 9th or early Chi ( Uppercase Χ, Lowercase χ; Χι He is the 22nd letter of the Greek alphabet, pronounced as in English TeX is the abbreviation of τέχνη (ΤΕΧΝΗ – technē), Greek for both "art" and "craft", which is also the source word of technical. English speakers often pronounce it /ˈtɛk/, like the first syllable of technical.

The name is properly typeset with the "E" below the baseline and reduced spacing between the letters. This is done, as Donald Knuth mentions in his TeXBook, to distinguish ΤeΧ from other system names such as TEX, the Text EXecutive processor (developed by Honeywell Information Systems). ^[33] Fans like to proliferate names from the word “TeX” — such as TeXnician (user of TeX software), TeXpert, TeXhacker (TeX programmer), TeXmaster (competent TeX programmer), TeXhax, and TeXnique.

Community

Notable entities in the TeX community include the TeX Users Group, which publishes TUGboat and The PracTeX Journal, and Deutschsprachige Anwendervereinigung TeX, a large user group in Germany. TeX Users Group ( TUG) founded in 1980 for educational and scientific purposes provides an organization for those who have an interest in typography and TUGboat (ISSN 0896-3207 is a journal published three times per year by the TeX Users Group. The PracTeX Journal, or simply PracTeX, also known as PTC is an Online journal focussing on practical use of the TeX typesetting Deutschsprachige Anwendervereinigung TeX e V (short Dante e V

See also

• List of document markup languages
• Comparison of document markup languages
• MathML
• Formula editor
• Texvc
• PSTricks

References

Notes

External links

• Plain TeX Quick Reference (PDF)
• UK TeX Users' Group FAQ
• Simon Eveson. An Introduction to Mathematical Document Production Using AmSLaTeX.
• The TeX showcase gallery of typesetting examples
• Eijkhout, Victor. TeX by Topic
• TeX for the Impatient (PDF)
• Walsh, Norman. Making TeX Work

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