On Expansion in Eigenfungtions of Boundary Value Problems V

The present paper is concerned with the problem of absolute convergence of Fourier series of f(x, y) given by f(x,y)∼Σa_nω_n(x,y)                             (1)

ω_n(x,y) being the eigenfunctions of

Δω + μω = 0; ω(x,y) = 0 on C                                                        (2)

corresponding to the eigenvalues μ_n.