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Re: Kahan's Floating Point Test
- To: dewar at gnat dot com
- Subject: Re: Kahan's Floating Point Test
- From: Geoff Keating <geoffk at geoffk dot org>
- Date: Thu, 31 May 2001 17:59:53 -0700
- CC: tprince at computer dot org, gcc at gcc dot gnu dot org
- References: <20010601002540.032DFF289D@nile.gnat.com>
- Reply-to: Geoff Keating <geoffk at redhat dot com>
> From: dewar@gnat.com
> Cc: gcc@gcc.gnu.org
> Date: Thu, 31 May 2001 20:25:40 -0400 (EDT)
>
> <<Even those (old) PowerPC architectures where all computations are done
> in double precision should have single-precision IEEE arithmetic fully
> supported in GCC; GCC will add appropriate rounding instructions when
> necessary.
> >>
>
> That's not quite good enough, due to double rounding phenomena
It is OK between double precision and single precision; double
rounding can't happen there because there are enough bits in a
'double'. It's not OK between the Intel 80-bit extended precision and
double precision.
--
- Geoffrey Keating <geoffk@geoffk.org>