In this paper, the value of deviation of a function f from its nth generalized de la Vallee-Poussin mean V-n(alpha)(lambda, f) with respect to the nonlinear trigonometric system is estimated for the classes of 2 pi-periodic ...

Let f be an H-periodic continuous function. The approximation order of the function f by deferred Cesaro means of its hexagonal Fourier series is estimated in uniform and generalized Holder metrics.