Christoph Rudolff

Christoph Rudolff (born 1499 in Jawor, Silesia, died 1545 in Vienna) was a German mathematician, 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").

[2] He introduced the radical symbol (√) for the square root.

It is believed that this was because it resembled a lowercase "r" (for "radix"),[3][4] though there is no direct evidence.

[5] Cajori only says that a "dot is the embryo of our present symbol for the square root"[6] though it is "possible, perhaps probable" that Rudolff's later symbols are not dots but 'r's.

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