Christoph Gudermann (March 25, 1798 - September 25, 1852) was born in Vienenburg, Germany. He was the son of a school teacher and became a teacher himself after studying at the University of Gottingen, where his advisor was Karl Friedrich Gauss. He began his teaching career in Kleve and then transferred to a school in Muenster. While there, Karl Weierstrass took Gudermann's course in elliptic functions, the first to be taught in any institute. Weierstrass was greatly influenced by this course, which marked the direction of his own research. March 25 is the 84th day of the year in the Gregorian calendar (85th in leap years). ... 1798 was a common year starting on Monday (see link for calendar). ... September 25 is the 268th day of the year (269th in leap years). ... 1852 was a leap year starting on Thursday (see link for calendar). ... The Georg-August University of Göttingen (Georg-August-Universität Göttingen, often called the Georgia Augusta) was founded in 1734 by George II, King of Great Britain and Elector of Hanover, and opened in 1737. ... Johann Carl Friedrich Gauss Johann Carl Friedrich Gauss (Gauß) (April 30, 1777 - February 23, 1855) was a legendary German mathematician, astronomer and physicist with a very wide range of contributions; he is considered to be one of the greatest mathematicians of all time. ... Map of Germany showing Cleves Cleves (in German Kleve, sometimes used in English as well; Dutch: Kleef) is a city in the north-west of North Rhine-Westphalia in Germany, near the Dutch border and the river Rhine, at 51° 47 North 6° 11 East. ... Münster: Prinzipalmarkt Münster is a city in North Rhine-Westphalia, Germany. ... Karl Theodor Wilhelm Weierstraß (October 31, 1815 – February 19, 1897) was a German mathematician who is often cited as the father of modern analysis. (The letter ß may be transliterated as ss; one often writes Weierstrass. ... In complex analysis, an elliptic function is, roughly speaking, a function defined on the complex plane which is periodic in two directions. ...

His researches into spherical geometry and special functions focused on particular cases, so that he did not receive the credit given to those who published more general works. Spherical geometry is the geometry of the two-dimensional surface of a sphere. ... In mathematics, several functions are important enough to deserve their own name. ...

The Gudermannian, or hyperbolic amplitude, is named after him. Gudermannian function with its asymptotes y = ±π/2 marked in gray. ...

Gudermann died in Muenster.

• Biography (http://www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Gudermann.html) at the MacTutor archive