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Re: Patch gcc-4.0 should not apply mathematical associative rulesfor addition or multiplication
On Thu, 7 Oct 2004, Richard Henderson wrote:
> On Thu, Oct 07, 2004 at 10:10:57PM +0000, Joseph S. Myers wrote:
> > A previous discussion of this sort of thing mentioned the case of x * 0.25
> > == 0 but x * 0.5 == x so x * 0.5 * 0.5 != x * 0.25, for small x and
> > rounding towards positive infinity with -frounding-math.
>
> Hmm? For what X does this hold? I can't find one for floats.
I can't find a reference to this discussion right now and I think it must
have been some other rounding mode, but the idea was that half the
smallest floating point value rounded to the same value but a quarter of
it rounded to zero
--
Joseph S. Myers http://www.srcf.ucam.org/~jsm28/gcc/
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