Astronomer and mathematician of the King Alfonso I the Battler Jew. It is very likely to be form in Huesca, still Muslim, even though he/she would later occupy important public office in Barcelona (Savasorda and Nasi of the Jewish communities). He/She highlighted their scientific knowledge, especially in the field of mathematics, astronomy and astrology, and philosophy, and was the first to write in Hebrew on many of those issues, creating for this purpose necessary terminology. He/She translated several scientific works from Arabic into latin in collaboration with Plato of Tivoli.
In his encyclopedic work, "Yesode has-t? bunah u-migdal has-emunah", «Fundamentals of intelligence and Tower of faith» (translated by J. M. Millás in 1952), addresses issues related to geometry, arithmetic, optics and music. His mathematical writings were soon translated into latin and helped introduce in Europe fundamental knowledge of geometry and trigonometry. His work Hibbur has-mesihah we-have-tisboret, «Dealt with the measurement and calculation» (translated by J. M. Millás in 1931), would serve to facilitate the measurement of the reconquered lands. In the field of astronomy exposes the system ptolomaico in Hebrew: Hokmat has-hizzayon, «Science of observation», is a work divided into two parts: Surat ha - ares, «Shape of the Earth», of cosmography (translated by J. M. Millás in 1956) and Heshbon mahalakot has-kokabim, «Calculation of the marches of the stars» (translated by J. M. Millás in 1959). Dealt also with problems of the calendar in the Sefer has-Cibbur, "Book of the collation", and made astronomical and astrological tables. In Megillat has-megalleh, «Roll Developer» (translated into catalan by J. M. Millás, Barcelona: 1929), announces the imminent coming of the redemption from astrology and perspectives of platonic philosophy; "Hegyon has-Zale has-asubah", «Reflection of the sad soul», is a philosophical and ethical work.
MILLÁS VALLICROSA, J. M. Literatura hebraicoespanola. 3rd ed. (Buenos Aires: work, 1973).
SÁENZ-BADILLOS, A. Hebrew literature in medieval Spain. (Madrid: Fundación Amigos de Sefarad, 1991).
SÁENZ-BADILLOS, TARGARONA, J. Dictionary of Jewish authors (Sefarad. 10th - 15th centuries). (Córdoba: El Almendro, 1990).