Swedish mathematician who showed in 1966 that, if a function is squarewise integrable, then its Fourier series is convergent from nearly every point. This announcement caused a stir because, earlier, Kolmogorov had shown that functions existed that could be integrated but whose Fourier series were divergent. While seemingly abstract and of little common interest, methods of Fourier analysis are important, for example, in reducing scientific data, computer enhancement of "grainy" photos, and looking for signs of intelligent life using interstellar radio signals.