Abū Saʿīd al-Jurjānī, Muḥammad b. ʿAlī Ḍarīr, was a Persian mathematician and astronomer. There is no information available on his biography. Sezgin argues that he probably lived around the 3rd/9th century (Sezgin, 5/263); however, Hogendijk (p. 47) discounts this and argues, based on al-Jurjānī's mention of the 4th/10th century scholar Abū ʿAbd Allāh al-Shannī, that he must have flourished around 390/1000. Following Flügel (p. 147), and without referring to any pri…