Let with for all j,k ≥ 1. We estimate the integral in terms of the coefficients , where α, β ∈ ℝ and ϕ: [0,∞] → [0,∞]. Our results can be regarded as the trigonometric analogues of those of Mazhar and Móricz [MM]. They generalize and extend Boas [B, Theorem 6.7].
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-sm156-2-4, author = {Chang-Pao Chen and Ming-Chuan Chen}, title = {Weighted integrability of double cosine series with nonnegative coefficients}, journal = {Studia Mathematica}, volume = {157}, year = {2003}, pages = {133-141}, zbl = {1021.42002}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-sm156-2-4} }
Chang-Pao Chen; Ming-Chuan Chen. Weighted integrability of double cosine series with nonnegative coefficients. Studia Mathematica, Tome 157 (2003) pp. 133-141. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-sm156-2-4/