Abū al-ʿAlāʾ Bihishtī, ʿAlāʾ al-Dīn Muḥammad b. Aḥmad al-Bayhaqī al-Isfarāyinī, known as Fakhr-i Khurāsān (d. 749/1348), a jurist and mathematician. He is also known by the names Aḥmad b. Muḥammad and Muḥammad b. Muḥammad, as well as by the epithets Shams al-Dīn and Fakhr al-Dīn. There is little information about him, and scholars have marked differences of opinion as to when he lived. Some are of the view that he lived in the 9th/15th and 10th/16th centuries (Mudarris, 244–245; Āstān-i Quds, Fihrist, 8, 159; Brockelmann, I/293, 470; II/273; S…