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MathGroup Archive 2004

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  • To: mathgroup at
  • Subject: [mg46433] Question
  • From: jjaeckel <jjaeckel at>
  • Date: Wed, 18 Feb 2004 00:36:57 -0500 (EST)
  • Sender: owner-wri-mathgroup at


I have a question about Integrate:

If I want to compute a completely real integral, e.g.

Integrate[(2*p^2*q^2*y^2 + p^3*q*y - p^2*q^2 + p*q^3*y + q^4)*1/(q^2)*1/(
           q^2 + 2*p*q*y + p^2) - 1, {y, -1, 1}, {q, 0, ?}]

I quite often get a complex result, e.g. in this case
(for Mathematica 5.0)


Moreover, in Version 4.2 seems to produce a different result. E.g. if I 
evaluate the above result for p=1 I get


but if I do the same calculation using Mathematica 4.2 I get


What did I do wrong?

Sorry if this question isn't new...


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