Charles George Broyden

Charles George Broyden (1933-2011) was a mathematician who specialised in optimization problems and numerical linear algebra. Working as a physicist at the English Electric Company from 1961 to 1965, he adapted the Davidon-Fletcher-Powell formula to nonlinear systems of equations, which led to his widely cited 1965 paper on methods for solving nonlinear simultaneous equations. He was a lecturer at the University College of Wales, Aberystwyth, from 1965 to 1967 and then a senior lecturer at the University of Essex until 1970, where he independently discovered the Broyden-Fletcher-Goldfarb-Shanno method, which became a key technique for nonlinear optimization. He also took part in deriving the symmetric rank-one updating formula, and his name is attached to Broyden's methods and the Broyden family of quasi-Newton methods. He later worked in the Netherlands and Italy and held a chair at the University of Bologna, and in his later years he turned to numerical linear algebra, especially conjugate gradient methods. The Charles Broyden Prize, established in 2009, honours his work, and he died in 2011.