Abstract. The aim of the paper is to generalize two fundamental theorems of K.~Tandori. The coefficient sequences in his theorems are classical monotone decreasing. We moderate the classical monotonicity to locally almost monotonicity assumption.

DOI: 10.14232/actasm-013-777-5

AMS Subject Classification (1991): 42A20, 42A16

Keyword(s): orthogonal series, coefficient conditions, locally almost monotonicity

Received April 25, 2013, and in revised form June 3, 2013. (Registered under 27/2013.)