反例-Fejér级数

Fejér example of a continuous function with divergent Fourier series. Fejér example is the even, \((2\pi)\)-periodic function \(f\) defined on \([0, \pi]\) by:

\[ f(x)=\sum_{p=1}^{\infty}\frac{1}{p^{2}}\mathrm{sin}\Bigl[(2^{p^{3}}+1)\frac{x}{2}\Bigr] \]