Summability of a sequence of Fourier coefficients by a triangular matrix transformation
H. P. Dikshit · Proceedings of the American Mathematical Society · 1969
in which the elements of the matrix D = ((dnk)) are real or complex constants. The sequence {u n} is called the sequence of D-means of {Sn }. If limn-,oo un exists and is equal to u then we say that the series 2Vn or the sequence { Sn } is summable D to the sum u. Let I pn } be a sequence of constants, real or complex, and let us write Pn=Po+pl+ * +pnO, P-1=p-1=O. Then the matrix D defines a Norlund matrix (N, pn) [6] if