2019/01/01 by Paris, R B
#33C05 #33C10 #33C20 #41A30 #41A60 #Classical Analysis and ODEs (math.CA) #FOS: Mathematics
paper · doi:10.48550/arxiv.1901.00142
We examine convergent representations for the sum of a decaying exponential and a Bessel function in the form ∑n=1^∞ \frace-an((1)/(2) bn)ν Jν(bn), where Jν(x) is the Bessel function of the first kind of order ν>-1/2 and a, b are positive parameters. By means of a double Mellin-Barnes integral representation we obtain a convergent asymptotic expansion that enables the evaluation of this sum in the limit a→ 0 with b<2π fixed. A similar result is derived for the sum when the Bessel function is replaced by the modified Bessel function Kν(x). The alternating versions of these sums are also mentioned.