On 6/6/09, Richard Fateman <fateman at cs.berkeley.edu> wrote:
> There is a IEEE floating-point object (really a large number of them)
> called NotaNumber (NaN) which has this contagious property.
> Perhaps this could be used, though treatment of NaNs by different Lisp
> systems may not be consistent.
> GCL or perhaps wxmaxima refuses to print a NaN. (to make one, I first
> made an infinity by (expt 2.0 50000) and then (- infinity infinity)
> should be a NaN.)
As an aside, that won't work. Lisp implementations aren't
required to handle NaN; some do, some don't.
GCL is inconsistent about NaN and +/- infinity. It can compute
them, but it can't display them. I guess that's a bug.
best
Robert Dodier