Although Sharaf al‐Dīn al‐Ṭūsī is known especially for his mathematics (in particular his novel work on the solutions of cubic equations), he was also the inventor of the linear astrolabe, a tool that derives from the planispheric astrolabe but is more easily constructed. From his name we may infer that Sharaf al‐Dīn was born in the region of Ṭūs, in northeastern Iran. He spent a major part of his early career as a teacher of the sciences, including astronomy and astrology, in Damascus and Aleppo; he also taught in Mosul. Among his students was Kamāl al‐Dīn ibn Yūnus, who would eventually teach Sharaf’s namesake, the great Naṣīr al‐Dīn al‐Ṭūsī.
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