born 1114, Biddur, India
died 0441; 1185, probably Ujjain
The leading mathematician of the 12th century.
He was the lineal successor of Brahmagupta as head of an astronomical observatory at Ujjain, the leading mathematical centre of ancient India. His mathematical works were the first to make full and systematic use of the decimal system. He evidently was the first to gain some understanding of the meaning of division by zero. He used letters to represent unknown quantities, much as in modern algebra, and solved indeterminate equations of 1st and 2nd degrees. He wrote on his astronomical observations of planetary positions, conjunctions, eclipses, cosmography, geography, and the mathematical techniques and astronomical equipment used in these studies. He was also a noted astrologer.