ON A THEOREM OF CHUI

Let f∈C_(2π) and let α_0/2+sum from k=1 to ∞ (a_k coskx+b_k sinkx) (1)be its Fourier series. Denote by S_n(f, x) the n-th partial sumof series (1) and by ω(f,δ) the modulus of continuity of functionf(x). For each q0, the Euler (E, q)-mean of series (1) is