Peter Bex writes: > On Mon, Apr 30, 2012 at 03:41:10AM -0400, John Cowan wrote: > > Peter Bex scripsit: > > > > > What about (rationalize x y) where x or y are nan or inf? The > > > notation seems to indicate that nan is allowed, since it's "real > > > but not rational". However, that same sentence seems to > > > indicate that rationalizing NaN would be an error. > > > > Rationalizing infinity makes some sense, but rationalizing NaN > > does not, at least not to me. > > What would the result be then? According to the spec, both the > infinities and NaN are rational but not real so infinity is out, > and I don't see any sane value other than infinity (or maybe nan) > as output for, say (rationalize +inf.0 1).
The construction of the Stern-Brocot tree that I've seen (related to the notion of the simplest rational in an interval) starts with two extreme "values", 0/1 and 1/0. All positive rationals are built between these. The pretense is that 1/0 is the simplest rational representation of "infinity". So it may make sense to return +inf.0. (Does the spec really say "rational but not real"?) _______________________________________________ Scheme-reports mailing list [email protected] http://lists.scheme-reports.org/cgi-bin/mailman/listinfo/scheme-reports
