Algorithm 793: GQRAT—Gauss quadrature for rational functions
ACM Transactions on Mathematical Software (TOMS)
On a conjecture of Clark and Ismail
Journal of Approximation Theory
Asymptotic approximations to the Hardy-Littlewood function
Journal of Computational and Applied Mathematics
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The function in question is H(x)=@?"k"="1^~sin(x/k)/k. In deference to the general theme of this conference, a summation procedure is first described using orthogonal polynomials and polynomial/rational Gauss quadrature. Its effectiveness is limited to relatively small (positive) values of x. Direct summation with acceleration is shown to be more powerful for very large values of x. Such values are required to explore a (in the meantime disproved) conjecture of Alzer and Berg, according to which H(x) is bounded from below by -@p/2.