
Boost Users : 
Subject: Re: [Boostusers] Spherical Bessel function (nu, x as real) implementation
From: John Maddock (jz.maddock_at_[hidden])
Date: 20160226 06:47:25
> 1)
> Does you use this reference to compute Spherical Bessel Functions for
> real argument?
>
> Accurate recursive generation of spherical Bessel and Neumann
> functions for a large range of indices
> E. Gillman <http://scitation.aip.org/content/contributor/AU0510272>^1
> and H. R. Fiebig
> <http://scitation.aip.org/search?value1=H.+R.+Fiebig&option1=author&option912=resultCategory&value912=ResearchPublicationContent>Comput.
> Phys. 2, 62(1988); http://dx.doi.org/10.1063/1.168296
>
They're implemented in terms of the regular (nonspherical) functions 
please see the documentation for full details.
> 2) is there a way to speed up the computation of j_nu(x) if one wants
> 10 digits accuracy for instance?
Yes, by way of an experiment suggest you define:
BOOST_MATH_PROMOTE_DOUBLE_POLICY=false
BOOST_MATH_DIGITS10_POLICY=10
at the start of the compilation unit (or on the command line). The
second one will make only a small difference to speed, the first can
make as much as a 2x difference on Linux x64.
HTH, John.
Boostusers list run by williamkempf at hotmail.com, kalb at libertysoft.com, bjorn.karlsson at readsoft.com, gregod at cs.rpi.edu, wekempf at cox.net