Re: +-Inf and NaN
Stavros Macrakis <[email protected]> Mon, 26 Feb 2024 11:53:31 -0500
| Newsgroups | gmane.comp.mathematics.maxima.general,gmane.lisp.gcl.devel |
|---|---|
| Message-ID | <CACLVabXZgiD27=PvsSvXC+1HtiPUjTdGO1ALUpTp9uNKDRx_PQ@mail.gmail.com> |
On Mon, Feb 26, 2024 at 9:51 AM Camm Maguire <[email protected]> wrote: > > On Fri, Feb 23, 2024 at 12:20 PM Henry Baker <[email protected]> > wrote: > ... > > One of these days (ha ha), we'll even get Maxima to realize that > > INF-INF does not equal 0, > > COMPILER>(- +inf +inf) > #<-nan> I was referring specifically to *Maxima **inf*, which is currently implemented as the symbol *$inf* and where the symbolic expression *(sub '$inf '$inf) *simplifies to *0*. The problem with symbolic calculations is similar to the compiler optimization issue -- can you simplify *(sub $x $x*) to *0*, knowing that some time later, someone may substitute *$inf* for *$x*; similarly, can you simplify *(div $x $x) *to *1*, knowing that *0 *may be substituted for *$x*? Maxima currently blithely assumes that's OK. There are proposals to keep track of implicit assumptions (called "caveats") so the simplification of *(sub $x $x*) would be *0 {caveat: $x is a number} *(i.e., not *INF,* *IND*, or *UND*). -s _______________________________________________ Maxima-discuss mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/maxima-discuss