fl. 900s

Persian astronomer and mathematician. Like many astronomers, Kushyar approached mathematics as an aid to his work, and took a particular interest in trigonometry, studying tangent functions and assembling new astronomical tables. Perhaps Kushyar's most famous work is Kitab fi usul hisab al-hind (translated in 1965 as Principles of Hindu Reckoning), in which he examined arithmetic as practiced in India. He also wrote on astrology.