There are two special numbers, 
and
, which may not be expressed as above.
Since numbers are stored in a fixed number
of bits these ``infinities'' are very useful. Both
of these numbers are members of all of our floating
point number systems. Many properties of these
special numbers are intuitive. For example:
The floating point number can represent
a real number too large to be described by a finite
number of 
. Similar sign infinities are incomparable.
Both 
and 
are false,
since it is unknown which real number each
represents.
| Jeff Tupper | March 1996 |