Re: Floating Point Approximations.

From: paul c <toledobythesea_at_oohay.ac>
Date: Thu, 29 Mar 2007 13:02:53 GMT
Message-ID: <1OOOh.86011$DN.78881@pd7urf2no>

David Cressey wrote:
> "paul c" <toledobythesea_at_oohay.ac> wrote in message
> news:fSBOh.84735$zU1.64713_at_pd7urf1no...
>

>>Bob Badour wrote:
>>
>>>David Cressey wrote:
>>> ...

> Likewise the programmer who uses Oracle math for amortization calculations.
>
> Regardless of whether you're a programmer or a user, this problem is going
> to surface as soon as you start using a computer for arithmetic. Of course
> some people think that using a computer for arithmetic is as quaint as using
> duct tape to seal ducts. On The Red Green show, one guy expressed amazement
> that duct tape can be used for that, too.
>
> Anyway, Paul, you and I are on the same page on this issue. Ordinary
> commerce should use exact representations for decimal fractions.

Yes, I'd say same page as Bob B too, who reminded me how slim the Intel support was (and still is, I assume), where the bcd instructions would operate on only one byte. The only other point I was trying to make in my clumsy way was that some machines, such as the IBM 360/370/390's going back all the way to the mid-1960's allowed fixed point bcd up to 16 bytes and besides the binary float (which was different from the IEEE one) also had a decimal float instruction set, so you didn't have to write a loop to add, subtract, multiply or divide two decimal float numbers.

I think the current big cpu manufacturers are cavalier and lazy about this.

p Received on Thu Mar 29 2007 - 08:02:53 CDT