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Re: Is this normal for Limit?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg82270] Re: [mg82241] Is this normal for Limit?
  • From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
  • Date: Wed, 17 Oct 2007 03:45:47 -0400 (EDT)
  • References: <200710160723.DAA08676@smc.vnet.net>

On 16 Oct 2007, at 16:23, Michael Mandelberg wrote:

> I have what I would think is the following simple limit to evaluate:
>
> $Pre = Refine[#] &;
> $Assumptions = {t \[Element] Reals, k \[Element] Reals,  k > 0};
>
> In[3]:= Limit[Exp[-k t], t -> Infinity]
>
> The results is:
>
> Out[3]= Limit[\[ExponentialE]^(-k t), t -> \[Infinity]]
>
> In other words Mathematica 6.0.0 punts on this.  Is there any sense in
> which this limit is not well-defined?
>
> Michael Mandelberg
>
>

$Assumptions is not working properly. I think this has already been  
pointed out on this list a while ago.

Limit[E^((-k)*t), t -> Infinity,
   Assumptions -> k > 0]
0

Andrzej Kozlowski




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