Sharaf al-Dīn al-Muẓaffar ibn Muḥammad ibn al-Muẓaffar al-Ṭūsī known more often as Sharaf al-Dīn al-Ṭūsī or Sharaf ad-Dīn aṭ-Ṭūsī, was an Iranian mathematician and astronomer of the Islamic Golden Age. Wikipedia