This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
Re: Improve tgamma accuracy (bug 18613) [committed]
- From: Joseph Myers <joseph at codesourcery dot com>
- To: Szabolcs Nagy <szabolcs dot nagy at arm dot com>
- Cc: "libc-alpha at sourceware dot org" <libc-alpha at sourceware dot org>
- Date: Thu, 2 Jul 2015 13:40:16 +0000
- Subject: Re: Improve tgamma accuracy (bug 18613) [committed]
- Authentication-results: sourceware.org; auth=none
- References: <alpine dot DEB dot 2 dot 10 dot 1506292329590 dot 25673 at digraph dot polyomino dot org dot uk> <alpine dot DEB dot 2 dot 10 dot 1507012145120 dot 29365 at digraph dot polyomino dot org dot uk> <55953573 dot 6070200 at arm dot com>
On Thu, 2 Jul 2015, Szabolcs Nagy wrote:
> hm i tried to verify this on aarch64 and also regenerate the libm ulps
>
> but the new ulps file somehow become much smaller than expected
>
> $ grep Function NewUlps
> Function: Real part of "cexp_downward":
> Function: Imaginary part of "cexp_downward":
> Function: Real part of "cexp_towardzero":
> Function: Imaginary part of "cexp_towardzero":
> Function: Real part of "cexp_upward":
> Function: Imaginary part of "cexp_upward":
> Function: Real part of "csin_upward":
> Function: Real part of "csinh_downward":
> Function: "jn_downward":
> Function: "jn_towardzero":
> Function: "jn_upward":
> Function: "tgamma_downward":
> Function: "tgamma_towardzero":
> Function: "tgamma_upward":
>
> so most functions have no errors and 'make regen-ulps'
> has no error output.
Those are the cases for which tests were only recently added (previously
not tested in all rounding modes). But NewUlps is created by adding the
new ulps to the old ones, not just taking the new ones on their own. (I
recommend truncating the libm-test-ulps file in the source tree before
running "make regen-ulps" anyway, so that you get ulps reductions as well
as increases and new ulps.)
A proper from-scratch regeneration (starting with the existing file
truncated) should give you a file very similar to the mips64 update I
recently checked in, since both use the same floating-point formats and
neither has custom versions of any libm functions whose results aren't
exactly determined.
--
Joseph S. Myers
joseph@codesourcery.com