William Velvel Kahan (born June 5, 1933, in Toronto, Ontario, Canada) is a mathematician and computer scientist whose main area of contribution has been numerical analysis.
He attended the University of Toronto, where he received his Bachelor's degree in 1954, his Master's degree in 1956, and his Ph.D. in 1958, all in the field of mathematics.
Among his many contributions, Kahan was the primary architect behind the IEEE 754 standard for floating-point computation (and its radix-independent follow-on, IEEE 854) and developed the Kahan summation algorithm, an important algorithm for minimizing error introduced when adding a sequence of finite precision floating point numbers.
He received the Turing Award in 1989, and was named an ACM Fellow in 1994.
Kahan is now a professor of mathematics, computer science, and electrical engineering at the University of California, Berkeley, and continues his contributions to the ongoing revision of IEEE 754.