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

Rudolff was from 1517 to 1521 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.

He introduced the radical symbol (√) for the square root. It is believed that this was because it resembled a lowercase "r" (for "radix"),[1][2] though there is no direct evidence.[3] Cajori only says that a "dot is the embryo of our present symbol for the square root"[4] though it is "possible, perhaps probable" that Rudolff's later symbols are not dots but 'r's.[5]

Furthermore, he used the meaningful definition that x0 = 1.

* History of mathematical notation

Notes

1. ^ a b Walter William Rouse Ball (1960), A short account of the history of mathematics (4 ed.), Courier Dover Publications, p. 215, ISBN 9780486206301, http://books.google.com/books?id=_sT_psl3uYkC&pg=PA215&dq=rudolf%20radix
2. ^ a b Howard Whitley Eves (1983), Great moments in mathematics (before 1650: Volume 1), MAA, p. 131, ISBN 9780883853108, http://books.google.com/books?id=9_w5jDPTvCQC&pg=PA131&dq=christoff+radix
3. ^ [1]
4. ^ a b Florian Cajori (1919), A history of mathematics (2 ed.), The Macmillan Company, p. 140, http://books.google.com/books?id=bBoPAAAAIAAJ&pg=PA140&dq=radix
5. ^ a b Florian Cajori (1993 (reprint)), A history of mathematical notations, Volumes 1-2, Courier Dover Publications, p. 369, ISBN 9780486677668, http://books.google.com/books?id=7juWmvQSTvwC&pg=PA369&dq=christoff+rudolff+radix

References

* Wolfgang Kaunzner, Karl Röttel: Christoff Rudolff aus Jauer in Schlesien, Polygon-Verlag, 2006, ISBN 3-928671-39-1.
* Moritz Cantor: Rudolff: Christoff R.. In: Allgemeine Deutsche Biographie (ADB). volume 29, Duncker & Humblot, Leipzig 1889, p. 571 f. (German)
* Wolfgang Kaunzner: Rudolff, Christoff. In: Neue Deutsche Biographie (NDB). volume 22, Duncker & Humblot, Berlin 2005, p. 198. (German)