On strong approximation of Nörlund and Euler means of orthogonal series. (English) Zbl 0794.40005
Summary: The authors have generalised the result proved by L. Leindler [Approximationstheorie. Abh. z. Tagung Oberwolfach, 4.–10. Aug. 1963, 239-244 (1964; Zbl 0134.051)] to Nörlund means which is obtained under the weaker condition in comparision with those taken by V. A. Bolgov and A. V. Efimov [Math. USSR, Isv. 5 (1971), 1399-1417 (1972; Zbl 0249.42018)]. The strong approximation of Nörlund and Euler means are also obtained in this paper.
MSC:
40G05 | Cesàro, Euler, Nörlund and Hausdorff methods |
42C15 | General harmonic expansions, frames |
40A05 | Convergence and divergence of series and sequences |