[r6rs-discuss] [Formal] NaN is not a real number.

[David Cuthbert]

Aubrey Jaffer wrote:
> +inf.0 and -inf.0 are real numbers because they are part of the total
> ordering of that subset of the real numbers represented in Scheme.

There is also a concept of complex infinity (infinite magnitude,
indeterminate argument).  For completeness, if NaN were to become a
complex number, there should be a concept of complex infinity (separate
from the two real infinities, though).