d. c. 1180
The son of Jewish immigrants, from his educated parents he learned medicine and science, and was self-taught in mathematics. At eighteen he had read all the mathematics he could find, and began writing his own. His surviving mathematical work brings together all the known algebraic rules of his age. A highly successful physician, he traveled widely in this capacity, and wrote on various medical topics. A treatise on sexology, and an anti-astrological work still survive.