Characterizations of double Hausdor matrices and best approximation of conjugate of a function in generalized H¨older space

Abstract

In the present paper, we obtain characterization results of double Hausdor matrices and apply
these results to obtain error estimation of the function ˜ f (x; y); conjugate to a function f (x; y) (periodic
with period 2 in both x and y) in generalized H¨older space by double Hausdor means of
its double conjugate Fourier series. Some important corollaries are also obtained from our main
result.