Immanuel ben Jacob Bonfils (c. 1300 – 1377) was a French-Jewish mathematician and astronomer in medieval times who flourished from 1340 to 1377, a rabbi who was a pioneer of exponential calculus and is credited with inventing the system of decimal fractions.
[1] He taught astronomy and mathematics in Orange and later lived in Tarascon, both towns in the Holy Roman Empire that are now part of modern-day France.
This was a forerunner to Simon Stevin, the first to widely distribute publications on this topic, and employed decimal notation for integers, fractions, and both positive and negative exponents.
[2][6][7] While living in Tarascon in 1365, Bonfils published the work for which he would become best known, Sepher Shesh Kenaphayim (Book of Six Wings) (Hebrew: שש כנפים), a manuscript on eclipses that featured astronomical tables predicting future solar and lunar positions (divided into six parts).
[1][8] The book included data for every important date on the Jewish calendar and even correction factors necessary for those who lived as far away as Constantinople.