Wrong limits



On 11/2/07, Richard Fateman wrote:
> Mathematica 6.0 gives +infinity for both directions, as well as undirected.
> It has been suggested here, recently, that the limit calculations should be
> reprogrammed along the lines of a recent PhD dissertation by Dominik Gruntz.
>
>  I think your example answers your own question about whether you can really
> trust the current program :)
>

Axiom replies:

 [leftHandLimit= - infinity, rightHandLimit=  + infinity]

I am surprised because I did not expect that Axiom's methods are that
different than Maxima's. (Axiom doesn't use Gruntz.)

Regards,
Bill Page.

On Friday, November 02, 2007 8:33 AM Paul Smith wrote:
>
> Take the code:
>
> (%i1)
> h:-(k^(k/(k-1))*(2*k-1)*2^(k/(k-1)))/((k-1)*(k*2^((2*k)/(k-1))
-2^((2*k)/(k-1))-2*k+1))$
>
> (%i2) limit(h,k,1/3,plus);
>                                       log(3)
>                                       ------
>                                         2
>                                   3 %e
> (%o2)                             -----------
>                                   160 sqrt(2)
> (%i3) limit(h,k,1/3,minus);
>                                       log(3)
>                                       ------
>                                         2
>                                   3 %e
> (%o3)                             -----------
>                                   160 sqrt(2)
> (%i4)
>
> Both limits are wrong: the first one is +oo and the second one is -oo.
> Can one really trust Maxima regarding the calculation of limits?
>