death_date death_place birth_place nationality fields birth_date image article_title name
29 august 1873 schramberg , tübingen halle german mathematical analysis special functions 14 february 1839 hankel.jpeg hermann hankel
 hermann hankel
hermann hankel

hermann hankel -lrb- 14 february 1839 -- 29 august 1873 -rrb- was a german mathematician who was born in halle , germany and died in schramberg -lrb- near tübingen -rrb- , imperial germany .
he studied and worked with , among others , möbius , riemann , weierstrass and kronecker .
his 1867 exposition on complex numbers and quaternions is particularly memorable .
for example , fischbein notes that he solved the problem of products of negative numbers by proving the following theorem : `` the only multiplication in r which may be considered as an extension of the usual multiplication in r + by `` respecting the law of distributivity '' to the left and the right is that which conforms to the rule of signs . ''
furthermore , hankel draws attention to the linear algebra that hermann grassmann had developed in his `` extension theory '' in two publications .
this attention was the first of many notations later made to grassmann 's early insights on the nature of space .
