Herbert B. Keller, Professor of Applied Mathematics, Emeritus, at the California Institute of Technology, passed away on Saturday, January 26. He was 82 years old.

Keller, a native of Paterson, New Jersey, earned his PhD in mathematics from New York University in 1954. After working as a research scientist and associate professor at the Courant Institute of Mathematical Sciences at NYU, he arrived at Caltech in 1965 as a visiting professor. He became a full professor two years later. At Caltech, Keller served as an executive officer for applied mathematics and director of Caltech's branch of the Center for Research on Parallel Computation. He retired in 2000 but remained an active researcher, attending seminars, workshops, and conferences related to his fields of interest.

At his 70th birthday celebration at Caltech in 1995, Keller was honored for his many contributions to applied math and scientific computation, including several innovative techniques to solve two-point boundary-value problems, which arise in such diverse areas as fluid mechanics, quantum physics, and electromagnetism. He is also credited with pioneering developments in bifurcation theory. Keller's methods are the basis for computer software that is widely used to derive numerical solutions to nonlinear equations. He also coauthored a classic numerical-analysis textbook with Eugene Isaacson, an eminent numerical analyst who had worked with Keller at the Courant Institute.

Keller is survived by his brother Joseph, a retired mathematics and mechanical engineering professor at Stanford University; a son, Steve, who lives in Bainbridge Island, Washington; a daughter, Debra, in Sacramento, California; and four grandchildren.