> On 3 Nov 2018, at 13:26, Antoniotti Marco <antoniotti.ma...@disco.unimib.it> > wrote: > > > >> On Nov 3, 2018, at 24:54 , Bob Cassels <bobcass...@netscape.net> wrote: >> >> Of course they are represented internally the same way other floating point >> values are. >> >> 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? > > Thank you. > > I do not really care about printing and reading NaNs and it looks like most > implementations do read and write IEEE infinities. > > Th problem is that ANSI does not talk about infinities and NaNs, so the issue > I have is what to do with them in a “portable” library (YMMV). > > I was toying with the idea of using symbolic constants for infinities, but it > looks like using IEEE infinities directly is a better - and simpler - way to > follow.
Note that there are a big number of NANs. If you want to print them readably, you definitely need a syntax able to deal with all of them, not just a couple of infinities. -- __Pascal J. Bourguignon__
