On Mon, 16 Jan 2012 04:21:37 -0800 (PST) Dima Pasechnik <dimp...@gmail.com> wrote:
> Once again, let me bring up the numerical noise issue on ARM. > The problem is that while we pretty much narrowed it down to a > particular function computing the log of the gamma-function, > lgammal, in elibc, an implementation of libc used on Ubuntu 11.10 (on > ARM, at least), the chances that the upstream fixes it seem to be > rarher slim. Fixing it myself does not look trivial – this C code is > not at all pretty, uses a lot of hardwired largish > constants, etc etc (and we cannot just patch a system library easily > anyway, so it needs to get into the upstream, etc etc...) > > I can produce doctest patches that will to the appropriate rounding, > but this potentially would make the corresponding doctests less > reliable (we talking about things like 120.0 vs 199.99999997 for > gamma(float(6)), something like this). > > As far as I know, doctests cannot be OS-dependent. > Any way out of this Catch-22? I guess this is the same problem as #9162. We should call a more reliable lgamma() function on these platforms. IIRC, the cephes package was included in Sage for this purpose. We could call the lgam() from cephes in sage/symbolic/pynac_cc.h to fix this. Cheers, Burcin -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
