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Problem with integration

  • To: mathgroup at smc.vnet.net
  • Subject: [mg123687] Problem with integration
  • From: Mehdi Mortazawi <mehdimortazawi at gmail.com>
  • Date: Thu, 15 Dec 2011 04:56:46 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com

Hi,
I was curious if there is difference between online Mathematica and
the one I have installed on my MAC(Mathematica version: 8.0.4.0).
The question rises from the problem that I am facing with numerical
integration. I want to integrate the following equation:

NIntegrate[e^(-x) ((1 + 2 x)/(1)) (BesselK[0, 2 Sqrt[x] Sqrt[1+x]]
+BesselK[2, 2 Sqrt[x] Sqrt[1 + x]]) + (4 x^2 +2 x-1)*BesselK[1, 2
Sqrt[x] Sqrt[1+x]]*e^(-x)/((1)Sqrt[x] Sqrt[1 + x]),{x,0,1}]

When I type the equation on my computer, I receive the following
message:
" ...has evaluated to non-numerical values for all sampling points in
the region with boundaries {{0,1}"
but the online version gives the following answer which is the value I
am expecting:

http://www.wolframalpha.com/input/?i=NIntegrate[e^%28-x%29+%28%281+%2B+2+x%29%2F%281%29%29+%28BesselK[0%2C+2+Sqrt[x]+Sqrt[1%2Bx]]%2BBesselK[2%2C+2+Sqrt[x]+Sqrt[1+%2B+x]]%29+%2B+%284+x^2+%2B2+x-1%29*BesselK[1%2C+2+Sqrt[x]+Sqrt[1%2Bx]]*e^%28-x%29%2F%28%281%29Sqrt[x]+Sqrt[1+%2B+x]%29%2C{x%2C0%2C1}]



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