This is the mail archive of the
gsl-discuss@sources.redhat.com
mailing list for the GSL project.
Re: Bug in Jacobi elliptic functions
- To: "Ivan E. Panchenko" <ivan at xray dot sai dot msu dot ru>
- Subject: Re: Bug in Jacobi elliptic functions
- From: Brian Gough <bjg at network-theory dot co dot uk>
- Date: Fri, 27 Apr 2001 12:09:28 +0100 (BST)
- Cc: gsl-discuss at sources dot redhat dot com
- References: <Pine.LNX.4.21.0104260756200.5090-100000@xray.sai.msu.ru>
- Reply-To: gsl-discuss at sources dot redhat dot com
Ivan E. Panchenko writes:
> There is a bug, probably in the algorithm itself.
> When one calculates dn(x) by gsl_sf_elljac_impl at _exactly_
> one half of its period, dn(0) is returned instead.
Thanks for the bug report -- stepping through the code shows that the
algorithm suffers from loss of precision at that point due to
cancellation errors. Jerry, is there some way to avoid this?