Signed infinity and signed zero Re: [Maxima] proposal to change acos



-----Richard Fateman wrote: -----

>If you have +inf and -inf you should also have +0
>and -0, and 0/0= undef. (projective mode)

Maxima does have 'zerob' (zero below, I believe) and
'zeroa' (zero above).  Limit knows something about
zeroa and zerob:

(%i96) limit(zeroa);
(%o96) 0
(%i97) limit(1/x,x,zeroa);
(%o97) inf
(%i98) limit(1/x,x,zerob);
(%o98) minf

But most of Maxima doesn't know anything about 'zeroa'
or 'zerob.'  Maybe we could make the IEEE 0.0+ --> zeroa
and 0.0- --> zerob?

Barton