A study of the theorem of Fejer and Kolmogorov

Abstract

In this project we study about criterion of the convergence of Fourier series. We also drive Dirichlet kernel and partial sum of Fourier series of function. Then we discuss Kolmogorov which states that There are functions belonging to 𝐿1 , whose Fourier series diverges almost everywhere and fejer theorem which states that Let f ∈𝐶2𝜋 and 𝑇𝑛 is arithmetic mean of partial sum of Fourier series of f.