Hajjaj bin Yusuf bin Matar was a mathematician and translator who worked in Baghdad between the end of the 8th century and the first quarter of the 9th century. He is known as the person who first translated Euclid's work called Elements from Greek into Arabic.
What is known about his life is extremely little; The years of birth and death are not exact. Sources place him active between approximately 786 and 830. He was among the first generation of the large translation movement carried out in Baghdad during the Abbasid period.
Translations
He translated the Elements twice. He prepared the first translation for Caliph Harun Rashid's vizier, Yahya bin Khalid; This text is called the Haruni copy. In the 820s, during the reign of Caliph Me'mun, he revisited the work and produced a more compact and shorter version; This second translation, known as the Me'munî copy, is considered more regular than the first. The work is also known as Usulu'l-Hendese in Arabic.
He also translated Ptolemy's fundamental work in astronomy, the Almagest, into Arabic. This translation is considered one of the early and decisive steps in the transfer of Greek mathematics and astronomy to the Islamic world.
