Editing TeX (section)

=== TeX82 ===
TeX82, a new version of TeX rewritten from scratch, was published in 1982. Among other changes, the original [[hyphenation algorithm]] was replaced by a new algorithm written by [[Frank Liang]]. TeX82 also uses [[fixed-point arithmetic]] instead of [[floating-point arithmetic|floating-point]], to ensure reproducibility of the results across different computer hardware,{{sfn|Knuth|Plass|1981|p=144}} and includes a real, [[Turing completeness|Turing-complete]] programming language, following intense lobbying by Guy Steele.<ref>Knuth, Donald E. ''[http://maps.aanhet.net/maps/pdf/16_15.pdf Knuth meets NTG members]'', NTG: MAPS. '''16''' (1996), 38–49. Reprinted as ''Questions and Answers, III'', chapter 33 of ''Digital Typography'', p. 648.</ref> In 1989, Donald Knuth released new versions of TeX and [[Metafont]].<ref>Knuth, Donald E. [http://www.tug.org/TUGboat/Articles/tb10-3/tb25knut.pdf ''The New Versions of TeX and METAFONT''], TUGboat '''10''' (1989), 325–328; '''11''' (1990), 12. Reprinted as chapter 29 of ''Digital Typography''.</ref> Despite his desire to keep the program stable, Knuth realized that 128&nbsp;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-bit]] inputs, allowing 256 different characters in the text input. TeX3.0 was released on March 15, 1990.<ref>{{Cite book |last=Hoenig |first=Alan |url=https://books.google.com/books?id=-xzeQtE4y0kC&dq=TeX82+published+in+1982&pg=PA8 |title=TeX Unbound: LaTeX & TeX Strategies for Fonts, Graphics, & More |date=1998 |publisher=Oxford University Press |isbn=978-0-19-509686-6 |language=en}}</ref>

Since version 3, TeX has used an idiosyncratic [[software versioning|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 [[Pi|{{pi}}]]. 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 3.141592653; it was last updated in 2021.<ref>{{cite web|title=TeX 21 release|url=http://ftp.cs.stanford.edu/pub/tex/tex21.tar.gz|access-date=2022-01-05}}</ref> 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 [[Software bug|bug]] fixes.<ref name=":1">{{Cite web|url=https://texfaq.org/FAQ-TeXfuture|title=What is the future of TeX?|date=2018-05-27|website=The TeX FAQ|access-date=2019-07-21|archive-date=28 April 2019|archive-url=https://web.archive.org/web/20190428184722/https://texfaq.org/FAQ-TeXfuture|url-status=dead}}</ref> 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 {{pi}}, at which point all remaining bugs will become features.<ref>Knuth, Donald E. [http://www.ntg.nl/maps/05/34.pdf ''The future of TeX and METAFONT''], NTG journal MAPS (1990), 489. Reprinted as chapter 30 of ''Digital Typography'', p. 571.</ref> Likewise, versions of Metafont after 2.0 asymptotically approach {{Mvar|[[E (mathematical constant)|e]]}} (currently at 2.7182818), and a similar change will be applied after Knuth's death.<ref name=":1" />