Simeon ben Zemah Duran

Simeon ben Zemah Duran, also Tzemach Duran (1361–1444) (Hebrew: שמעון בן צמח דוראן), known as Rashbatz (רשב"ץ) or Tashbatz was a Rabbinical authority, student of philosophy, astronomy, mathematics, and especially of medicine, which he practised for a number of years at Palma (de Majorca). A major 15th century posek, his published decisions in matters of halacha have been widely quoted in halachic literature for hundreds of years.