Person: Nemorarius, Jordanus
Jordanus Nemorarius was a German scholar who wrote several books on arithmetic, algebra, geometry and astronomy. He was among the first to use letters to replace numbers in algebraic calculations.
Mathematical Profile (Excerpt):
 Perhaps the most significant fact is a very negative one, namely that Jordanus de Nemore's name does not appear in any list of clerics so it is generally assumed that he was a layman.
 On the positive side we note that Richard de Fournival, who was Chancellor of the Cathedral of Amiens, made a list of works which were desirable for the Cathedral library in 1250 and four works by Jordanus appear.
 This was, for quite some time, thought to have been written by Jordanus so proving that he taught at Toulouse.
 The second controversy among scholars regarding Jordanus is whether Jordanus de Nemore and Jordanus de Saxonia are the same person.
 It is known that Jordanus de Saxonia was the first successor to Saint Dominic as the Grand Master of the Dominicans.
 This is fair evidence that the two Jordanus's are the same person but it is far from conclusive.
 What we do know of Jordanus is his works, many of which have survived.
 Jordanus was the first to correctly formulate the law of the inclined plane.
 There are six mathematical treatises written by Jordanus.
 In De numeris datis Jordanus gives results on solving quadratic equations similar to those given by alKhwarizmi except general forms are given rather than the numerical examples of the earlier text.
 The proofs given by Jordanus, like those of alKhwarizmi, are by the method of completing the square.
 In astronomy Jordanus used letters to denote the magnitudes of stars (not unrelated to his use of letters for algebraic notation).
 Jordanus visited the Holy Land and, on the return journey, he lost his life at sea.
Born 1225, Borgentreich (near Warburg), Germany. Died 1260, At sea.
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Origin Germany
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Epochs: 1
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References
Adapted from other CC BYSA 4.0 Sources:
 Oâ€™Connor, John J; Robertson, Edmund F: MacTutor History of Mathematics Archive