Christopher Browne <cbbrowne@libertyrms.info> writes:
> This _seems_ a cosmetic difference, or am I way wrong?
I think you can ignore it. It's odd that your setup seems to support
minus zero (else there'd be more diffs) but doesn't get the right answer
for this single computation. Still, it's basically a roundoff issue,
and as such a legitimate platform-specific behavior.
regards, tom lane