Prove that the given sum is not Fourier series

74 Views Asked by At

Book browsing Banach spaces of Analytic function of the author Kenneth Hoffman on page 74 is one example. This example is compiled in this way:

Prove that

$$ \sum_{n=1}^{\infty}\frac{1}{\log n}e^{in\theta} $$

is not the Fourier series of a finite measure on the circle.

I would like to know how is the solution communities in this example. Previously, thank you for solving.

1

There are 1 best solutions below

0
On

Look at the theorem on p.23. It says that a formal Fourier series is the Fourier series of a finite measure if and only if the Cesaro means are bounded in $L^1$. Check this.