Is the maximum error bound in __mul really 1.001ULP?

[Joseph S. Myers]

On Sat, 20 Apr 2013, Siddhesh Poyarekar wrote:

> > A conclusion that the error bound is less than 0.5ulp (that is, ulps of a
> > value with the precision to which the result gets rounded) is implausible.
> > If you get such a conclusion I suppose you must be counting ulps in some
> > way different from the statement that the bound is 1.001ulp.
> 
> Agreed, which is why I posted my derivation too.  Do you think there's
> something wrong with it?

I didn't see any point in analysis of the derivation when the conclusion 
clearly doesn't make sense.

-- 
Joseph S. Myers
joseph@codesourcery.com