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] Florian 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. [7]
Furthermore, he used the meaningful definition that x0 = 1.
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