On 21/04/14 19:39, Bear wrote: > On Mon, 2014-04-21 at 14:18 -0400, John Cowan wrote: >> Bear scripsit: >> >>> If you get +inf.0 instead, that's still nonsense (because you multiplied >>> something finite by something finite, mathematically you should have >>> a finite result) >> >> It's not nonsense, actually. Inexact numbers can be interpreted as >> intervals, and +inf.0 can then be identified with the open interval >> (1.79769313486231570e+308, \infty). So when you get +inf.0 from >> multiplying two exact numbers, you are being told with 100% correctness >> that the answer falls into that interval. >> > > In asserting that it is not nonsense, you must allow that Scheme > is using the word "infinity" (represented as +inf.0) in a way > that is foreign to mathematics and only tangentially related to > its mathematical meaning. > > It is sensible in terms of programming language semantics. But > someone who knew only traditional mathematical semantics would > have no way to guess the programming language semantics, and > would find them opaque.
Perhaps it is worth our wording around what "inexact numbers" means explicitly referring to intervals, then? > > Bear > ABS -- Alaric Snell-Pym http://www.snell-pym.org.uk/alaric/
signature.asc
Description: OpenPGP digital signature
_______________________________________________ Scheme-reports mailing list [email protected] http://lists.scheme-reports.org/cgi-bin/mailman/listinfo/scheme-reports
