Journal of Inequalities and Applications 
Volume 4 (1999), Issue 3, Pages 241-264
doi:10.1155/S1025583499000387

Weighted uniform approximation on the semiaxis by rational operators

B. Della Vecchia,1 G. Mastroianni,2 and J. Szabados3

 1Dipartimento di Matematica, Università degli Studi di Roma “La Sapienza”, Piazzale Aldo Moro 2, Roma 00185, Italy
2Dipartimento di Matematica, Università della Basilicata, Via Nazario Sauro 85, Potenza 85100, Italy
3Mathematical Institute of the Hungarian Academy of Sciences, P.O.B. 127, Budapest H-1364, Hungary
Received 9 November 1998; Revised 10 December 1998

Abstract

We construct rational operators for the weighted uniform approximation on the semiaxis. Direct and converse results are shown which are not possible for polynomials.