The New International Encyclopædia/Regiomontanus

REGIOMONTANUS (1436-76). A German mathematician and astronomer, whose real name was Johannes Müller. He was born near Königsberg (whence his Latin name), was educated at Vienna, and was a pupil of Georg Peuerbach (q.v.). He collected numerous Greek MSS. and translated many of them, especially the works of Ptolemy, Apollonius, Archimedes, and Hero of Alexandria. He also brought the algebra of Diophantus to the notice of Europeans. Regiomontanus was the author of a treatise on plane and spherical trigonometry. De Trianqulis Omnimodis (1533), which contained the sine and cosine. Adopting the half chord of the Arabs, he constructed tables of sines and tangents. His work on arithmetic and algebra, entitled Algorithmus Demonstratus (1534), was among the first containing symbolic algebra. He established an observatory and printing press in Nuremberg, and produced tables of eclipses, and works on astronomy and astrology. He was called to Rome by Sixtus IV. to revise the calendar, but died there the following year, and was buried in the Pantheon. His works include: Ephemerides ab Anno 1475-1506 (1474); Calendarium Novum (1473); De Quadratura Circuli (1463); Disputationes Dialogus contra Gerhardi Cremonensis in Planetarum Theorias Deliramenta (1475); De Reformatione Calendarii (1484); De Cometæ Magnitudine Longitudineque (1531); Tabulæ Directionum Profectionumque (1575); De Doctrina Triangulorum (1463). Consult Ziegler, Regiomontanus (Dresden, 1874). A collection of his letters was edited by Murr (Nuremberg, 1786).