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Re: Solving an integral in the limit.
 To: mathgroup at smc.vnet.net
 Subject: [mg62417] Re: Solving an integral in the limit.
 From: "JensPeer Kuska" <kuska at informatik.unileipzig.de>
 Date: Wed, 23 Nov 2005 06:27:28 0500 (EST)
 Organization: Uni Leipzig
 References: <dm11o7$e0s$1@smc.vnet.net>
 Sender: ownerwrimathgroup at wolfram.com
Hi,
when the integrand is extended into the complex plane,
one may be able to compute the defined integral without
finding the undefined integral and take the limit.
Regards
Jens
"Josef Karthauser" <joe at tao.org.uk> schrieb im
Newsbeitrag news:dm11o7$e0s$1 at smc.vnet.net...
 I'm having trouble solving a complicated
integral using mathematica,
 and I'm looking for some wisdom on the matter.

 The problem can be summarised as follows.
Mathematica can determine
 the solution to,

 Integrate[E^(I*x^2)/ Sqrt[1 + x^2], {x, 0,
Infinity}]

 but if I replace the upper bound with a free
variable and take the limit
 as it goes to Infinity mathematica doesn't
manage it,

 Limit[Integrate[E^(I*x^2)/ Sqrt[1 + x^2], {x,
0, a}], a > Infinity]

 Surely it should be able to determine that the
answer is the same as in
 the previous case. Is there anyway to pursuade
it?

 Many thanks,
 Joe
 
 Josef Karthauser (joe at tao.org.uk)
http://www.josefk.net/
 FreeBSD (cvs meister, admin and hacker)
http://www.uk.FreeBSD.org/
 Physics Particle Theory (student)
http://www.pact.cpes.sussex.ac.uk/
 ================ An eclectic mix of fact and
theory. =================

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