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Re: limit problem

• To: mathgroup at smc.vnet.net
• Subject: [mg58924] Re: limit problem
• From: "David W. Cantrell" <DWCantrell at sigmaxi.org>
• Date: Sun, 24 Jul 2005 01:21:46 -0400 (EDT)
• References: <dbt3lm$sk4$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

Chris Chiasson <chris.chiasson at gmail.com> wrote:
> Dear MathGroup,
> Honestly, I see no reason why this should return "unevaluated" instead of
> zero.
>
> FullSimplify[Limit[E^(-R t),t\[Rule]Infinity],Infinity>R>0&&Element[R,
> Reals]]
>
> 5.2 on windows

That seems like a good point. My guessplanation is that perhaps conditions
given for Simplify or FullSimplify are not used inside of Limit.

Note that one need not even ask for simplification if, _prior_ to asking
for the limit, it is specified that 0 < R < Infinity:

In[4]:= Assuming[0 < R < Infinity, Limit[E^(-R t), t -> Infinity]]

Out[4]= 0

using version 5.1 on Windows.

David