[PATCH] Update x86_64 ULPs

[Joseph S. Myers]

On Thu, 2 May 2013, Ondrej Bilka wrote:

> On Thu, May 02, 2013 at 02:55:20PM -0400, Carlos O'Donell wrote:
> > On 05/02/2013 02:49 PM, Joseph S. Myers wrote:
> > > On Thu, 2 May 2013, Ondrej Bilka wrote:
> > > 
> > >> Could we compute ulp directly with mpfr or I am missing some roadblock?
> > > 
> > > The whole point of ulps baselines is to record the errors produced by the 
> > > actual glibc implementation, compared to an exact expected result (which 
> > > quite likely was computed with MPFR).  Those baselines can, on x86 and 
> > > x86_64, depend on the processor implementation of the x87 instructions for 
> > > transcendental operations (so on whether an Intel or AMD processor is in 
> > > use, for example), as well as, on 32-bit x86, on the details of where the 
> > > compiler uses excess precision.
> > >
> 
> So mpfr computations depend on processor used?

No.  The difference between the exact result from MPFR, and the actual 
result from libm, depends on the actual result from libm, which depends on 
the processor used.  And the point of libm-test-ulps is to record the 
maximum expected values of those differences on each platform.

-- 
Joseph S. Myers
joseph@codesourcery.com