C. 1065 - 1136 C.1065-1136 ABRAHAM BAR HIYYA aka Savasorda (Spain)
Philosopher, astronomer, astrologer, and mathematician. He wrote numerous original works in Hebrew. These include Yesod ha-Tevunah u-Migdal ha-Emunah (The Foundation of Understanding and the Tower of Faith) an encyclopedia of math astronomy, optics, and music. His definite work on astronomy Khochmat ha-Chiza'yon consisted of two parts Tzurat ha-Aretz ve-Tavnit Kaddurei ha-Raki'a ("Form of the Earth and Figure of the Celestial Spheres ") and Kheshbon Mahalekhot ha-Kokhavim ("Calculation of the Courses of the Stars parts of which were translated into Latin. His Chibbur ha-Meshichah ve-ha-Tishboret (Treatise on Measurement and Calculation) (1116) was translated into Latin in 1145 by Plato of Tivoli as Liber Embadorum. It gave the area of a circle and helped introduce trigonometry to the west. He also translated many Arabic mathematical and scientific texts into Hebrew.