средние Валле–Пуссена

Approximation of Smooth Functions in Lp(x)2π by Vallee–Poussin Means

Variable exponent p(x) Lebesgue spaces Lp(x) is considered. For f ∈ Lp(x) Vallee–Poussin means Vnm(f, x) can be defined as Vnm(f, x) = 1/(m+1)Ʃl=0mSn+l(f, x), where Sk(f, x) –- partial Fourier sum of f(x) of order k. Approximative properties of operators Vnm(f) = Vnm(f, x) are investigated in Lp(x). Let p(x) ≥ 1 be 2π-periodical variable exponent that satisfies Dini–Lipschitz condition.