Re: IEEE arithmetic handling

> jlg@cochiti.lanl.gov (J. Giles) writes:
> This is easily accomplished. Let `b' be the base of your floating point
> representation and let `p' be the number of digits in your significand.
> Then, output followed by input is the identity if:
>
> (m-1) p
> 10 >= b - 1
>
> Where `m' is the number of decimal digits output.


This doesn't seem to work. Take an example: let b=2, p=4. Thus
  p
b - 1 = 15, so m=3. Now consider the binary number 1.001, which has
4 binary digits (as dicated by p=4). This number, in decimal, is exactly
1.125, which requires 4 decimal digits, thus exceeding the number m.


I don't believe any formula like the above can work if b contains a factor
that is not also a factor of 10 -- for instance, a b of 3 would never
work, since there are fractions in base 3 that are non-terminating
decimals. (Of course, a computer using base 3 would be pretty strange.
:-)


--
Bill Leonard
Harris Computer Systems Division
2101 W. Cypress Creek Road
Fort Lauderdale, FL 33309
bill@ssd.csd.harris.com
--

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