Bernard Widrow

Bernard Widrow (December 24, 1929 – September 30, 2025) was an American professor of electrical engineering at Stanford University known for his work on artificial neural networks. He co-invented the Widrow–Hoff least mean squares filter (LMS) adaptive algorithm with his doctoral student Ted Hoff. The LMS algorithm led to the ADALINE and MADALINE artificial neural networks, and to the backpropagation technique. He made fundamental contributions to the development of digital signal processing in the fields of geophysics, adaptive antennas, and adaptive filtering.

Widrow was the namesake of "Uncle Bernie's Rule": the training sample size should be ten times the number of weights in a network.