Obelus#In mathematics

{{main|Obelism}}

{{more|Dagger (typography)}}

The modern dagger symbol originated from a variant of the obelus, originally depicted by a plain line {{char|−}}, or a line with one or two dots {{char|⨪{{nbsp}}÷}}.{{cite book|title =Merriam-Webster's collegiate dictionary|publisher =Merriam-Webster, Inc|year =2003|page=[https://archive.org/details/merriamwebstersc00merr_6/page/855 855]|isbn =978-0-87779-809-5|url =https://archive.org/details/merriamwebstersc00merr_6|url-access =registration|quote =obelos.}} It represented an iron roasting spit, a dart, or the sharp end of a javelin,{{cite book|editor=William Harrison Ainsworth|title =The New monthly magazine|publisher =Chapman and Hall|volume=125|year =1862|page=1|url =https://books.google.com/books?id=PycaAQAAIAAJ&q=obelos&pg=PA1}} symbolizing the skewering or cutting out of dubious matter.

Originally, one of these marks (or a plain line) was used in ancient manuscripts to mark passages that were suspected of being corrupted or spurious; the practice of adding such marginal notes became known as obelism. The dagger symbol {{char|†}}, also called an obelisk,{{cite dictionary |dictionary = The Oxford English Dictionary (D{{ndash}}E |year=1933 |entry=Dagger (8) |page=[https://archive.org/details/the-oxford-english-dictionary-1933-all-volumes/The%20Oxford%20English%20Dictionary%20Volume%203/page/n18/mode/1up 7]}} is derived from the obelus, and continues to be used for this purpose.

The obelus is believed to have been invented by the Homeric scholar Zenodotus, as one of a system of editorial symbols. They marked questionable or corrupt words or passages in manuscripts of the Homeric epics.{{cite book|author=Harold P. Scanlin|editor=Alison Salvesen|title =Origen's Hexapla and fragments: papers presented at the Rich Seminar on the Hexapla, Oxford Centre for Hebrew and Jewish Studies, 25th-3rd August|publisher =Mohr Siebeck|year =1998|page=439|chapter=A New Edition of Origen's Hexapla: How It Might Be Done|isbn =978-3-16-146575-8|chapter-url =https://books.google.com/books?id=9xQDu27_HEIC&q=metobelos&pg=PA439}} The system was further refined by his student Aristophanes of Byzantium, who first introduced the asterisk and used a symbol resembling a {{char|⊤}} for an obelus; and finally by Aristophanes' student, in turn, Aristarchus, from whom they earned the name of "Aristarchian symbols".{{cite book|author=Paul D. Wegner|title =A student's guide to textual criticism of the Bible|publisher =InterVarsity Press|year =2006|page=194|isbn =978-0-19-814747-3|url =https://books.google.com/books?id=SIMsY6b2n2gC&q=obelos&pg=PA192}}{{cite book|author=George Maximilian Anthony Grube|title =The Greek and Roman critics|publisher =Hackett Publishing|year =1965|page=128|isbn =978-0-87220-310-5|url =https://books.google.com/books?id=jerucRW8UmMC&q=obelos&pg=PA128}}

In some commercial and financial documents, especially in Germany and Scandinavia, a variant ({{unichar|2052|commercial minus sign|nlink=}}) is used in the margins of letters to indicate an enclosure, where the upper point is sometimes replaced with the corresponding number.{{Cite book|url=https://www.unicode.org/versions/Unicode10.0.0/ch06.pdf#G7935|title=The Unicode® Standard, Version 10.0|publisher=The Unicode Consortium|year=2017|isbn=978-1-936213-16-0|location=Mountain View, CA|chapter=Writing Systems and Punctuation}} In Finland, the obelus (or a slight variant, $\backslash cdot\; \backslash !\; /\; \backslash !\; \backslash cdot$) is used as a symbol for a correct response (alongside the check mark, {{char|✓}}, which is used for an incorrect response).{{cite book|url=https://www.unicode.org/versions/Unicode10.0.0/ch06.pdf#G7935 | page=280, Commercial minus | chapter = 6. Writing Systems and Punctuation | publisher= Unicode Consortium | title = The Unicode® Standard: Version 10.0 – Core Specification | date= June 2017}}

In the 7.0 release of Unicode, {{unichar|2E13|Dotted obelos}} was one of a group of "Ancient Greek textual symbols" that were added to the specification (in the block Supplemental Punctuation).{{cite web |title=Supplemental Punctuation |url=https://www.unicode.org/charts//PDF/Unicode-7.0/U70-2E00.pdf | publisher=Unicode Consortium |date=2014}}

{{main|Division sign}}

File:Skjermbilete 2012-11-03 kl. 02.48.36.png

The form of the obelus as a horizontal line with a dot above and a dot below, {{char|÷}}, was first used as a symbol for division by the Swiss mathematician Johann Rahn in his book Teutsche Algebra in 1659. This gave rise to the modern mathematical symbol {{char|÷}}, used in anglophone countries as a division sign.{{cite web |url=http://www.pballew.net/arithme7.html |title=Math Words |page= 7 |publisher=Math Words Alphabetical Index |access-date=August 26, 2011 |archive-url=https://web.archive.org/web/20110807071158/http://www.pballew.net/arithme7.html |archive-date=August 7, 2011 |url-status=usurped |df=mdy-all}}{{Cite web |title=Division |url=https://www.mathsisfun.com/numbers/division.html |access-date=2020-08-26 |website=www.mathsisfun.com}} This usage, though widespread in Anglophone countries, is neither universal nor recommended: the ISO 80000-2 standard for mathematical notation recommends only the solidus {{char|/}} or fraction bar for division, or the colon {{char|:}} for ratios; it says that {{char|÷}} "should not be used" for division.ISO 80000-2, Section 9 "Operations", 2-9.6 The ambiguity of mathematical expressions that involve the obelus and implicit multiplication has become a subject of Internet memes.

This form of the obelus was also occasionally used as a mathematical symbol for subtraction in Northern Europe; such usage continued in some parts of Europe (including Norway and, until fairly recently, Denmark).{{citation|title=A history of mathematical notations (two volumes bound as one) |publisher=Dover |year=1993|isbn=9780486677668|first=Florian|last=Cajori|author-link=Florian Cajori|pages=242, 270–271|url=https://books.google.com/books?id=fNVYTRBTIJ8C&pg=PA270}}. Reprint of 1928 edition. In Italy, Poland and Russia, this notation is sometimes used in engineering to denote a range of values.{{cite book| url=https://www.unicode.org/versions/Unicode10.0.0/ch06.pdf#G7935 | page=280, Obelus | chapter = 6. Writing Systems and Punctuation | publisher= Unicode Consortium | title = The Unicode® Standard: Version 10.0 – Core Specification | date= June 2017}}

In some commercial and financial documents, especially in Germany and Scandinavia, another form of the obelus{{snd}} the commercial minus sign{{snd}} is used to signify a negative remainder of a division operation.{{cite book|title= Kaufmännische Arithmetik oder allgemeines Rechenbuch für Banquiers, Kaufleute, Manufakturisten, Fabrikanten und deren Zöglinge | author= Johann Philipp Schellenberg | page = 213| date=1825| lang=DE | trans-title= Commercial arithmetic or general arithmetic book for bankers, merchants, manufacturers, craftsmen and their pupils}}{{cite web |url=http://unicode.org/pipermail/unicode/2014-January/000013.html |title=Commercial minus as italic variant of division sign in German and Scandinavian context |author=Leif Halvard Silli |website=Unicode.org |access-date=2020-04-04 |archive-date=2019-06-14 |archive-url=https://web.archive.org/web/20190614233459/http://unicode.org/pipermail/unicode/2014-January/000013.html |url-status=dead }}

• {{anli|Manicule}} ({{big| ☞ }}) used for obelism.
• {{anli|Obelisk}}
• {{anli|Obelix}}
• {{anli|Obol (coin)}} also known as an obelos.
• List of typographical symbols and punctuation marks

{{Reflist}}

{{Wiktionary}}

Category:Typographical symbols