Eduard Stiefel

Eduard Stiefel (1909 to 1978) was a Swiss mathematician who worked first in topology and then turned to numerical mathematics. Born in Zürich, he studied at ETH Zurich and took his doctorate there in 1935 under Heinz Hopf with a thesis on direction fields in manifolds. His early work on vector fields, fibre bundles and Lie groups led to the Stiefel manifolds and to the Stiefel-Whitney characteristic classes, which he developed alongside Hassler Whitney. After becoming a full professor at ETH in 1943 he founded its Institute for Applied Mathematics in 1948, where a leased Zuse Z4 computer, and later the ERMETH built at the institute, made ETH the first university on the European continent to run a programmable computing machine. With Magnus Hestenes he developed the conjugate gradient method for linear systems in 1952, and with Paul Kustaanheimo he gave the regularization method for celestial mechanics that carries both names. He was president of the Swiss Mathematical Society in 1956 and of GAMM from 1970 to 1974.