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Re: [Scheme-reports] Numeric towers
Ray Dillinger scripsit:
> For what it's worth, I consider it worthwhile to have a limited range
> of exact ratios, where the results of (/) on exact arguments are exact
> if both numerator and denominator are within a bounded integer range
> and inexact otherwise.
Technically, systems without ratios already do this, but the denominator
is limited to 1.
> This provides "opportunistic" preservation of exactness where you could
> not ordinarily specify it due to the possibility of representation
It's an interesting idea, but AFAIK no Schemes provide it, so it is
not ripe for standardization.
> Type theorists objecting that they need to be able to statically
> determine the type of an operation without referent to the values
> of the arguments will object to the exact/inexact conversion implicit
> in bounded ratios.
We already have such things with EXPT.
> It is also important to programs to know whether exact and inexact
> numbers are interconvertible without changing numeric value. IE,
> whether the system supports the same precision in inexact numbers
> as exact numbers.
I don't know any systems that do this: it would require very artificial
restrictions on ratios to make them match IEEE flonums.
"Repeat this until 'update-mounts -v' shows no updates. John Cowan
You may well have to log in to particular machines, hunt down cowan@x
people who still have processes running, and kill them." www.ccil.org/~cowan
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