Abu Bakr Muhammad Ibn ‘Abd al-Bāqī al-Baghdadi al-Ansārī al-Kaabī (1050-1141) (Arabic: محمد بن عبد الباقي البغدادي) also known as Qadi al-Maristan, was an Arab jurist and mathematician. He was the author of a commentary on the tenth book of Euclid's Elements, which was translated by Gerard of Cremona as Liber judei super decimum Euclidis. The work was popular in Europe with several Latin manuscripts still extant. Other works include: