Abraham bar Hiyya
Abraham bar Hiyya (Abraham bar Ḥiyya ha - Nasi ), Abraham Judaeus or Savasorda (* around 1070 in Barcelona; † around 1136 possibly in Provence or Narbonne ), a Jewish, acting in Spanish Catalonia mathematician, moral philosopher was ( Neoplatonist ) astrologer and astronomer of the 12th century.
His Latinized name Savasorda comes from the Arabic ( watch captain, Sahib al - Shurta ), pointing to an official position (eg in the counts of Barcelona and the King of Aragon ) in his hometown of Barcelona, which was under Christian rule, but where then also were in use from the Arabic -derived names. His intimate knowledge of Arabic mathematics and astronomy, however, point to a longer stay in an Islamic center of learning such as Zaragoza, which was also the center of Jewish learning. Notes in his works also place a connection to Jewish circles close in Provence.
He is known for his Hebrew textbook on Islamic mathematics ( Ḥibbūr ha - ha - we- meshīḥah tishboret, essay on measurement and calculation ), which Plato translated 1145 Tivoli as Liber Embadorum into Latin. Included in this is the first complete treatment of the quadratic equation in the West, about the same time into Latin translated with the also in 1145 ( by Robert of Chester ) Algebra of al- Khwarizmi. The book influenced Fibonacci. He studied Arabic texts on the ancient Greek mathematician, Abraham ibn Ezra as well (1092 - 1167), and both are considered to be the founder of Jewish studies to mathematics in the Middle Ages. Among the studied him ancient mathematicians include Euclid, Apollonius of Perga, Theodosius of Bithynia, Autolycus of Pitane, Menelaus of Alexandria Heron of Alexandria, Eudemus of Rhodes and the Arabs Al- Khwarizmi and al - Karaji. As a translator, he worked together with the also acting in Barcelona Plato of Tivoli, wrote his own works but all in Hebrew.
He also published the first Hebrew Encyclopedia ( Yesod ha - Tebunah u - Migdal ha - Emunah, The foundations of knowledge and the tower of faith ) treated, mathematics, optics, astronomy, and music, astronomical texts, a book on moral philosophy ( Hegyon ha - Nefesh ha - Azuva, meditations of the sad soul), a book of astrological, historical theological and eschatological interpretations of history ( Megillat ha - Megalleh, scroll of Revelator ), in which he the coming of the Messiah for the year 1358 ( 5118 years after the creation) predicted, and a book on Jewish calendar calculation ( Sefer ha - Ibbur, 1122 /23) ( the oldest known Hebrew to work ), especially for the calculation of Jewish holidays.