Johann Rahn (Latinised form Rhonius) (10 March 1622 – 25 May 1676) was a Swiss

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, mathematical structure, structure, space, Mathematica ...

who is credited with the first use of the

division sign The division sign () is a mathematical symbol consisting of a short horizontal line with a dot above and another dot below, used in Anglophone countries to indicate the operation of division. This usage is not universal and the symbol has d ...

, ÷ (a repurposed

obelus 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: * Division sign * Dagger * Commercial minus sign (limited g ...

variant) and the therefore sign, ∴. The symbols were used in ''Teutsche Algebra'', published in 1659. John Pell collaborated with Rahn in this book, which contains an example of the Pell equation. It is uncertain whether Rahn or Pell was responsible for introducing the symbols.

Books

Teutsche Algebra
- Johann H. Rahn

Literature

*R. Acampora ''Johann Heinrich Rahn und seine Teutsche Algebra'', in R. Gebhardt (Herausgeber) ''Visier- und Rechenbücher der frühen Neuzeit'', Schriften des Adam-Ries-Bundes Annaberg-Buchholz 19, 2008, S. 163–178 * Moritz Cantor: Rahn, Johann Heinrich . In: General German Biography (ADB). Volume 27, Duncker & Humblot, Leipzig, 1888, pp. 174 f *Noel Malcolm, Jacqueline Stedall ''John Pell (1611–1685) and His Correspondence with Sir Charles Cavendish: The Mental World of an Early Modern Mathematician'', Oxford University Press, Oxford, 2005 * Christoph Scriba ''John Pell's English Edition of J. H. Rahn 's Teutsche Algebra'', in: R. S. Cohen (Herausgeber) ''For Dirk Struik'', Reidel: Dordrecht 1974, S. 261–274 * Jacqueline Stedall ''A Discourse Concerning Algebra: English Algebra to 1685'', Oxford University Press, Oxford, 2002

References

;general * Cajori, Florian. ''A History of Mathematical Notations''. 2 volumes. Lasalle, Illinois: The Open Court Publishing Co., 1928–1929 vol. 2, page 211. ;citations 1622 births 1676 deaths 17th-century Swiss mathematicians {{Europe-mathematician-stub

Books

Literature

See also

References