Abstract:
For a function $f\in L^1({\mathbb T})$, we investigate the sequence
$(C,1)$ of mean values $\Phi(|S_k(x,f)-f(x)|)$, where $\Phi
(t)\colon [0,+\infty)\to [0,+\nobreak \infty)$, $\Phi (0)=\nobreak 0$, is a
continuous increasing function. We prove that if $\Phi $ increases faster
than exponentially, then these means can diverge everywhere. Divergence
almost everywhere of such means was established earlier.
Keywords:Fourier series, means of Fourier series, the space $L^1({\mathbf T})$.