On Fri, Jun 16, 2000 at 01:44:01PM -0700, Dave Peticolas wrote:
>
> The reason why I like doubles is that a huge amount of work has gone
> into making the IEEE floating point specification "correct". These
> quantities are used ubiquitously and are scrutinized by many people.
> I have great confidence that the calculations are being done
> correctly. OTOH, if we roll our own numerical library, I will have
> much less confidence. It's not that I think we are bad developers,
> it's just that the problem is quite complicated. It took a long time
> to get IEEE floating point correct, and there were some extremely
> smart people involved.
>
> For that reason, if we decide to drop doubles, I would rather use
> a library like gmp which has already been written/debugged rather
> than start from scratch. We've got too many other things to do.
>
Let me point out that, so far as I know, no responsible accountant
would recommend uncorrected binary floating-point arithmetic for
bookkeeping, though it is used in economic modelling. A system where
1% of $10 is not 10 cents is not acceptable for bookkeeping! Interval
arithmetic <http://www.cs.utep.edu/interval-comp/main.html> would--I
think--solve this problem, but the standard for bookkeeping is IBM's
decimal arithmetic. A proposed version for Java, including a detailed
discussion and code can be seen at <http://www2.hursley.ibm.com/decimal/>.
--
Randolph Fritz
Eugene, Oregon, USA
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