# Christoph Rudolff

**Christoph Rudolff** (born 1499 in Jawor, Silesia, died 1545 in Vienna) was the author of the first German textbook on algebra.

From 1517 to 1521, Rudolff was a student of Henricus Grammateus (Schreyber from Erfurt) at the University of Vienna and was the author of a book computing, under the title: * Behend und hübsch Rechnung durch die kunstreichen regeln Algebre so gemeinicklich die Coss genent werden* (Nimble and beautiful calculation via the artful rules of algebra [which] are so commonly called "coss").

^{[1]}

He introduced the radical symbol (√) for the square root. It is believed that this was because it resembled a lowercase "r" (for "radix"),^{[2]}^{[3]} though there is no direct evidence.^{[4]} Cajori only says that a "dot is the embryo of our present symbol for the square root"^{[5]} though it is "possible, perhaps probable" that Rudolff's later symbols are not dots but 'r's.^{[6]}

Furthermore, he used the meaningful definition that *x*^{0} = 1.

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## NotesEdit

**^**Note: "Influenced by al-Khowarizmi and later Islamic writers who called the unknown [i.e., the variable*x*]*shai*, Arabic for "thing", Latin texts used*res*and those in Italian used*cosa*("thing"). In Italy, algebra became known as*l'arte della cosa*, in England as*cossike arte*, or*the rule of coss*, and in Germany,*die Coss*." Jan Gullberg,*Mathematics: From the Birth of Numbers*(New York, New York: W.W. Norton, 1997), page 299.**^**Walter William Rouse Ball (1960),*A short account of the history of mathematics*(4 ed.), Courier Dover Publications, p. 215, ISBN 978-0-486-20630-1**^**Howard Whitley Eves (1983),*Great moments in mathematics (before 1650: Volume 1)*, MAA, p. 131, ISBN 978-0-88385-310-8**^**"History of Mathematical Symbols" by Douglas Weaver and Anthony D. Smith, University of South Australia**^**Florian Cajori (1919),*A history of mathematics*(2 ed.), The Macmillan Company, p. 140**^**Florian Cajori (1993),*A history of mathematical notations, Volumes 1-2*(reprint ed.), Courier Dover Publications, p. 369, ISBN 978-0-486-67766-8

## ReferencesEdit

- Wolfgang Kaunzner; Karl Röttel; Christoff Rudolff (2006).
*Christoff Rudolff aus Jauer in Schlesien: zum 500. Geburtstag eines bedeutenden Cossisten und Arithmetikers, der aus diesem seinerzeit hoheitlich zur Krone von Böhmen gehörenden Landesteil stammt*[*Christoff Rudolff from Jauer in Silesia: on the 500th birthday of an important algebraist and arithmetician, who came from this region, which in his time belonged to the royal crown of Bohemia*]. ISBN 978-3-928671-39-2. - Moritz Cantor (1889), "Rudolff: Christoff R.",
*Allgemeine Deutsche Biographie (ADB)*(in German),**29**, Leipzig: Duncker & Humblot, pp. 571–572 - Wolfgang Kaunzner (2005), "Rudolff, Christoff",
*Neue Deutsche Biographie (NDB)*(in German),**22**, Berlin: Duncker & Humblot, p. 198 - O'Connor, John J.; Robertson, Edmund F., "Christoph Rudolff",
*MacTutor History of Mathematics archive*, University of St Andrews.

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