Dyes and Pigments.
Elsevier Ltd.
Vol. 158.
2018.
We obtain new conditions on periodic integrable functions so that their transformed Fourier series belong to Lp. This improves the classical Hardy and Bellman results. A counterpart for the Fourier transforms is also established. Our main tool is a new extension of the Hausdorff–Young–Paley inequality for Fourier transforms. © 2018 Elsevier Inc.