Shihab al-Din Ahmad bin Abu Bakr al-Sarraj al-Hamawi (d. 1328-29 AD) is the author of several books on scientific instruments and geometrical problems. Another copy of the present treatise al-Durr al-gharib fi al-'amal bi da'irat al-tajwid (Rare pearls on operations with the circle for finding sinuses), on sinus quadrants, is today at Leyden (187b/4). It was was dedicated to the Turkish Sultan Bayazid I.
See, Brockelmann, Geschichte der Arabischen Litteratur, S II, p. 327; and Catalogus Codicum Orientalium Bibl. Acad. Lugd., 1142