Battani, al-, (circa 858-929), leading Arab astronomer and mathematician of his time. Known also as Albatenius, his full name was Abu-Abdullah Muhammad ibn Jabir al-Battani. His astronomical observations at Raqqah, Syria, extended for a period of more than 40 years. He also made important contributions to pure mathematics. He introduced the use of sines in mathematical calculations, computed a table of cotangents, and formulated certain propositions in spherical trigonometry. His astronomical works, published as De Motu Stellarum (Concerning the Motion of the Stars, 1537), corrected errors of the Alexandrian astronomer Ptolemy in regard to the inclination of the ecliptic and the length of the year.