Caspar Wessel (June 8, 1745 - March 25, 1818) was a Norwegian-Danish mathematician. is the 159th day of the year (160th in leap years) in the Gregorian calendar. ... // Events May 11 - War of Austrian Succession: Battle of Fontenoy - At Fontenoy, French forces defeat an Anglo-Dutch-Hanoverian army including the Black Watch June 4 – Frederick the Great destroys Austrian army at Hohenfriedberg August 19 - Beginning of the 45 Jacobite Rising at Glenfinnan September 12 - Francis I is elected... is the 84th day of the year (85th in leap years) in the Gregorian calendar. ... Year 1818 (MDCCCXVIII) was a common year starting on Thursday (link will display the full calendar) of the Gregorian Calendar (or a common year starting on Tuesday of the 12-day slower Julian calendar). ... Leonhard Euler, considered one of the greatest mathematicians of all time A mathematician is a person whose primary area of study and research is the field of mathematics. ...

Wessel was born in Jonsrud, Vestby, Akershus, Norway. In 1763, having completed secondary school, he went to Denmark for further studies (Norway having no university at the time). In 1778 he acquired the degree of candidatus juris. From 1794, however, he was employed as a surveyor (from 1798 as Royal inspector of Surveying). County Akershus Landscape Follo Municipality NO-0211 Administrative centre Vestby Mayor (2003) Tom Anders Ludvigsen (Ap) Official language form BokmÃ¥l Area  - Total  - Land  - Percentage Ranked 367 134 km² 134 km² 0. ... County NO-02 Region Østlandet Administrative centre Oslo County mayor Hildur Horn Øien (KrF) Area  - Total  - Percentage Ranked 16 4,918 km² 1. ... 1763 was a common year starting on Saturday (see link for calendar). ... Year 1778 (MDCCLXXVIII) was a common year starting on Thursday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Monday of the 11-day slower Julian calendar). ... Surveyor at work with a leveling instrument. ...

It was the mathematical aspect of surveying that led him to exploring the geometrical significance of complex numbers. His fundamental paper, Om directionens analytiske betegning, was published in 1799 by the Royal Danish Academy of Sciences and Letters. Since it was in Danish, it passed almost unnoticed, and the same results were later independently found by Argand and Gauss. In mathematics, a complex number is a number which is often formally defined to consist of an ordered pair of real numbers , often written: In mathematics, the adjective complex means that the underlying number field is complex numbers, for example complex analysis, complex matrix, complex polynomial and complex Lie algebra. ... Royal Danish Academy of Sciences and Letters (Danish: Kongelige Danske Videnskabernes Selskab) is a Danish non-governmental science Academy, founded November 13, 1742 by permission of the King Christian VI, as a historical Collegium Antiquitatum. ... Jean-Robert Argand was an accountant and bookkeeper in Paris who was only an amateur mathematician. ... Johann Carl Friedrich Gauss (pronounced ,  ; in German usually Gauß, Latin: ) (30 April 1777 – 23 February 1855) was a German mathematician and scientist who contributed significantly to many fields, including number theory, statistics, analysis, differential geometry, geodesy, electrostatics, astronomy, and optics. ...

Wessel's priority to the idea of a complex number as a point in the complex plane is today universally recognised. His paper was re-issued in French translation in 1899, and in English in 1999 as On the analytic representation of direction (ed. J. Lützen et al.). In mathematics, the complex plane is a way of visualising the space of the complex numbers. ...

Caspar Wessel's elder brother Johan Herman Wessel was a major name in Norwegian and Danish literature. Johan Herman Wessel Johan Herman Wessel (October 6, 1742 - December 29, 1785) was a major name in Norwegian and Danish literature. ...

External links

• O'Connor, John J; Edmund F. Robertson "Caspar Wessel". MacTutor History of Mathematics archive.