[Maxima] [sympy] Re: [sage-support] Re: limit of floor
ondrej at certik.cz
Thu Jul 24 11:50:09 CDT 2008
On Thu, Jul 24, 2008 at 6:47 PM, Robert Dodier <robert.dodier at gmail.com> wrote:
> On Thu, Jul 24, 2008 at 4:25 AM, William Stein <wstein at gmail.com> wrote:
>> teragon-2:doc was$ sage -maxima
>> Maxima 5.13.0 http://maxima.sourceforge.net
>> (%i1) limit(floor(x),x,0,minus);
>> (%o1) 0
>> (%i4) limit(ceiling(x),x,0,plus);
>> (%o4) 0
> Well, that's obviously wrong. However in more recent versions
> limit returns noun expressions for floor and ceiling.
> That's not incorrect, but also not very helpful.
> Obviously it is desirable to get correct results for discontinuous
> functions. I'm not sure what is the best way to go about it.
> It would be easy to wire in special cases for floor(x) and
> ceiling(x), and that would help, but I don't know whether
> Maxima can infer results for more complex cases from that.
> Dan Gildea has been fixing a lot of bugs in the limit code
> (thanks very much, Dan). Maybe he can comment on this.
I am fixing this in sympy right now. The way to go imho is just to
make sure floor(x).series(x, 0, 5) is correct. (from the right hand
side) and from the left hand side. That's all that the gruntz
algorithm needs,then it should work, we'll see.
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