Obelus

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Template:Short description Template:For Template:Use British English

Three variants of obelus glyphs

Template:Infobox symbol Template:Special characters An obelus (plural: obeluses or obeli) is a term in codicology and latterly in typography that refers to a historical annotation mark which has resolved to three modern meanings:

The word "obelus" comes from Template:Wikt-lang (obelós), the Ancient Greek word for a sharpened stick, spit, or pointed pillar.[1] This is the same root as that of the word 'obelisk'.[2]

In mathematics, the first symbol is mainly used in Anglophone countries to represent the mathematical operation of division and is called an obelus.[3] In editing texts, the second symbol, also called a dagger mark Template:Char is used to indicate erroneous or dubious content;[4][5] or as a reference mark or footnote indicator.[6] It also has other uses in a variety of specialist contexts.

Use in text annotation

Template:See also Template:More The modern dagger symbol originated from a variant of the obelus, originally depicted by a plain line Template:Char, or a line with one or two dots Template:Char.[7] It represented an iron roasting spit, a dart, or the sharp end of a javelin,[8] symbolizing the skewering or cutting out of dubious matter.[9]

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 Template:Char, also called an obelisk,[10] 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.[9] The system was further refined by his student Aristophanes of Byzantium, who first introduced the asterisk and used a symbol resembling a Template:Char for an obelus; and finally by Aristophanes' student, in turn, Aristarchus, from whom they earned the name of "Aristarchian symbols".[11][12]

In some commercial and financial documents, especially in Germany and Scandinavia, a variant (Template:Unichar) is used in the margins of letters to indicate an enclosure, where the upper point is sometimes replaced with the corresponding number.[13] In Finland, the obelus (or a slight variant, ⋅/⋅) is used as a symbol for a correct response (alongside the check mark, Template:Char, which is used for an incorrect response).[14][15]

In the 7.0 release of Unicode, Template:Unichar was one of a group of "Ancient Greek textual symbols" that were added to the specification (in the block Supplemental Punctuation).[16]

In mathematics

Template:Main

Plus and minuses. The obelusTemplate:Snd or division signTemplate:Snd used as a variant of the minus sign in an excerpt from an official Norwegian trading statement form called «Næringsoppgave 1» for the taxation year 2010.

The form of the obelus as a horizontal line with a dot above and a dot below, Template: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 Template:Char, used in anglophone countries as a division sign.[17][18] This usage, though widespread in Anglophone countries, is neither universal nor recommended: the ISO 80000-2 standard for mathematical notation recommends only the solidus Template:Char or fraction bar for division, or the colon Template:Char for ratios; it says that Template:Char "should not be used" for division.[19] 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).[20] In Italy, Poland and Russia, this notation is sometimes used in engineering to denote a range of values.[21]

In some commercial and financial documents, especially in Germany and Scandinavia, another form of the obelusTemplate:Snd the commercial minus signTemplate:Snd is used to signify a negative remainder of a division operation.[22][14]

See also

References

Template:Reflist Template:Wiktionary

  1. ↑ Template:Cite book
  2. ↑ Template:Cite book
  3. ↑ Template:Cite web
  4. ↑ Template:Cite book
  5. ↑ Template:Cite book
  6. ↑ Template:Cite book
  7. ↑ Template:Cite book
  8. ↑ Template:Cite book
  9. ↑ 9.0 9.1 Template:Cite book
  10. ↑ Template:Cite dictionary
  11. ↑ Template:Cite book
  12. ↑ Template:Cite book
  13. ↑ Template:Cite book
  14. ↑ 14.0 14.1 Template:Cite web
  15. ↑ Template:Cite book
  16. ↑ Template:Cite web
  17. ↑ Template:Cite web
  18. ↑ Template:Cite web
  19. ↑ ISO 80000-2, Section 9 "Operations", 2-9.6
  20. ↑ Template:Citation. Reprint of 1928 edition.
  21. ↑ Template:Cite book
  22. ↑ Template:Cite book
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