Born Feb. 14, 1839, in Halle; died Aug. 29, 1873, in Schramberg. German mathematician.
Working in Erlangen and Tübingen, he derived a series of formulas on the theory of cylindrical functions; his researches on the foundations of arithmetic promoted the development of the theory of quaternions and general hyper-complex number systems. Hankel also wrote works on the history of mathematics in the classical and medieval periods.
WORKSTheorie der complexen Zahlensysteme. Leipzig, 1867. (Vorlesungen über die complexen Zahlen und ihre Funktionen, part 1.)
Zur Geschichte der Mathematick in Altertum und Mittelalter. Leipzig, 1874.