Approximation by double Walsh polynomials
Approximation by double Walsh polynomials
We study the rate of approximation by rectangular partial sums, Cesàro means, and de la Vallée Poussin means of double Walsh‐Fourier series of a function in a homogeneous Banach space X . In particular, X may be L p ( I 2 ), where 1≦ p < ∞ and I …