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Re: Implementation of read-ieee-float64
On 12/7/05, Bradley Lucier <lucier@xxxxxxxxxxxxxxx> wrote:
> Gambit 4.0b15 fails some srfi-56 tests because the first instance of
> 2.0 is not 2; unfortunately, Gambit-C calculates
> (expt 2.0 -1074)
> (/ (expt 2.0 1074))
Hi, thanks for looking into this and getting it working with Gambit.
The (expt 2.0 ...) form was there for the sake of Bigloo, for which
(expt N -M) => 0
for all exact integers N, M > 1. This is clearly a bug on Bigloo's
part, but it seemed safe to compensate for it. In particular, every
other tested implementation correctly evaluates (expt 2.0 -1024).
[Or so I thought. Scheme48 also gives 0.0 for this.]
Choosing between the lesser of two evil^H^H^H^Hbugs, I'd
consider Bigloo's behavior the more egregious here, so let's
call (expt 2 ...) the correct reference form.
Congratulations, Gambit now passes all tests!
[And possibly the latest version of Scheme48 does as well.]