Re: Something wrong with this integral (see text)
- To: mathgroup at smc.vnet.net
- Subject: [mg44436] Re: Something wrong with this integral (see text)
- From: "David W. Cantrell" <DWCantrell at sigmaxi.org>
- Date: Sun, 9 Nov 2003 06:01:24 -0500 (EST)
- References: <boif3m$oaf$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
"Ihor Stealth" <stealth at gmx.net> wrote:
> I calculated two expressions:
>
> FullSimplify[Integrate[(-L^2)/(L^2 + 1)*Cos[L], {L,0, Infinity}]]
>
> and
>
> FullSimplify[Integrate[(-1)/(L^2 + 1)*Cos[L], {L,0, Infinity}]]
>
> They gave the same result, but in the first expression when we take
> L->Infinity, it's impossible to take integral, but MAthematica CAN do
> that.
>
> What the explanation of this?
This question was posted, separately, by Ihor to sci.math, where it has
already been thoroughly answered.
In short, at least in version 5: The two integrals do not give the same
result, and for the first integral, Mathematica says "Unable to check
convergence."
David Cantrell