Are you asking how to print those values? (Print -0.0 like that. Print + and - infinity some way they can be read by the reader. Preferably some way that's not otherwise a legal token. Probably print NaNs using the #unreadable syntax. I don't remember how that works. I don't remember what we did at Symbolics, even though I'm probably the one who did it. I can ask around, if you care.) Or something else?