Am Dienstag, den 07.09.2010, 22:55 -0400 schrieb Raymond Toy:
> On 9/7/10 10:40 PM, Viktor T. Toth wrote:
> > Right now (testing with 5.21.0 and the current CVS), we have
> >
> > (%i3) limit(2/x-1/x,x,0);
> > (%o3) infinity
> >
> > but
> >
> > (%i6) limit(2/x,x,0)-limit(1/x,x,0);
> > (%o6) 0
> >
> > That just does not smell right.
> >
> > Shouldn't we have
> >
> > inf + inf = inf (NOT 2 inf),
> > inf - inf = und (NOT 0),
> > minf + minf = minf (NOT 2 minf),
> > minf - minf = und,
> > inf - minf = inf,
> > minf - inf = minf,
> > infinity + inf = infinity + minf = infinity + infinity = und,
> > infinity - inf = infinity - minf = infinity - infinity = und?
> I think these are all known bugs. I did some work on this but never
> finished it. I think Dieter has also done some work on this.
Yes, I have done last year an implementation to simplify infinities. The
implementation worked well with the testsuite and share_testsuite.
Unfortunately, I have lost this implementation. I had a problem with my
hard disk and no backup of the code. But it is not difficult to
implement it again. I only need some time.
Dieter Kaiser