2013-01-03 03:39:18 -0600 answered a question Arbitrary precision BesselY Didn't know about mpmath. It seems to provide all I need. Many thanks Frank 2013-01-03 03:38:25 -0600 received badge ● Scholar (source) 2013-01-03 03:38:25 -0600 marked best answer Arbitrary precision BesselY Try: sage: import mpmath sage: mpmath.bessely?  (mpmath is multiprecision package) 2013-01-03 02:52:57 -0600 asked a question Arbitrary precision BesselY Hi, I consider using Sage for some calculations which contain Bessel functions of complex arguments. Since I have to mix Bessel functions with very small and very large arguments I require precision higher than 15 digits. Unfortunately, I recognized that BesselY is not implemented in PARI. But BesselJ and BesselH1 are. My physicists understanding of math tells me, I could just use "(BesselH1-BesselJ)/i". But I am surprised that this has not been discussed before (at least I couldn't find it), since this would allow a quick implementation of BesselY. Am I missing something that's obvious for math experts? Or can I just use above definition to get an arbitrary precision BesselY? Many thanks Frank