Fourier coefficients and the approximation of functions by series in a periodic multiplicative system
The author considers the periodic multiplicative system of functions, presented by \textit{N. Ya. Vilenkin} in Izv. Akad. Nauk SSSR, Ser. Mat. 11, 363-400 (1947; Zbl 0036.356) and obtains estimates for block of partial sums of Fourier series and for the Fourier coefficients in various metrics.
scientific article; zbMATH DE number 3914933