Three constants are defined to support IEEE NaN's and infinities:
When printing an infinity or a NaN when *print-escape* is nil , the appropriate symbol is printed using the #. read macro. For example,
> positive-infinity #.POSITIVE-INFINITYThis insures that all numbers are printed in a readable form, even infinities. All NaN's are printed identically, there is no provision for preserving variations among NaN's.
There is currently no provision for checking for a NaN or infinity. There probably ought to be lisp equivalents of the IEEE-recommended functions isnan and finite.
At present the symbols used here are external in the XLISP package.As they are nonstandard, they should probably be internal in a system package.