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Re: Limit Question

  • To: mathgroup at
  • Subject: [mg66472] Re: Limit Question
  • From: "Stratocaster" <stotz1 at>
  • Date: Sun, 14 May 2006 02:58:31 -0400 (EDT)
  • References: <e43vun$90e$>
  • Sender: owner-wri-mathgroup at

"Blimbaum, Jerry CIV NSWC PC" <jerry.blimbaum at> wrote in message 
news:e43vun$90e$1 at
> Why do these give no output?
> Simplify[Limit[Exp[-a t],t->Infinity],a>0]
> and  same for
> Simplify[Limit[Exp[a t],t->Infinity],a<0]
> thanks...
> Jerry Blimbaum

Well, that is a pretty good question, although I probably cannot give the 
"best" answer I'll put my two cents in for what it's worth.

The first thing that comes to mind is the expressions and the values for 
"a."  Take for example the first expression.  IF "Exp[-a*t]" AND "a>0" THEN 
"t" must be negative.  So I suggest :


In which case you don't really need the "Simplify" or  the condition for 


I believe there is something similar going on in the second equation.  Make 
your limit expression correspond to your condition for "a" and you will not 
need to add anything extraneous to your "Limit" code.  I'm not sure if you 
just wanted to evaluate the limits or are asking specifics on why 
Mathematica isn't responding well to your input.  Hopefully this helps.

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