Ghiyāth ad-Dīn Abu'l-Fatḥ ʿUmar ibn Ibrāhīm al-Khayyām Nīshāpūrī (18 May 1048 – 4 December 1131; Persian: غیاث الدین ابوالفتح عمر ابراهیم خیام نیشابورﻯ, pronounced [xæˈjːɒ:m]) was a Persian polymath, philosopher, mathematician, astronomer and poet. He also wrote treatises on mechanics, geography, mineralogy, music, and Islamic theology.
Born in Nishapur, at a young age he moved to Samarkand and obtained his education there. Afterwards he moved to Bukhara and became established as one of the major mathematicians and astronomers of the medieval period. He is the author of one of the most important treatises on algebra written before modern times, the Treatise on Demonstration of Problems of Algebra, which includes a geometric method for solving cubic equations by intersecting a hyperbola with a circle. He contributed to a calendar reform.