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MathGroup Archive 1998

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Integration Problems

  • To: mathgroup at smc.vnet.net
  • Subject: [mg13926] Integration Problems
  • From: Georgios Kotsalis <kotsalis at mit.edu>
  • Date: Mon, 7 Sep 1998 01:22:51 -0400
  • Organization: Massachusetts Institute of Technology
  • Sender: owner-wri-mathgroup at wolfram.com

Dear Sirs ,

while performing the following evaluation, i received an unexpected
result:

1.) W1[x_,t_]:=
    q[2,1][t] (Sin[4.73 x] - Cos[4.73 x] + Exp[-4.73 x] + Exp[-4.73
(1-x)]);

2.) W2[x_,t_]:=Evaluate[(D[W1[x,t],{x,2} ])^2]

3.) Integrate[W2[x,t],{x,0,1}]

Answer:

(509.399 -2.922295 X 10^-5 I) q[2,1][t]^2

Could you please tell me, why does an imaginary part arise though the
function
that is being integrated is real ?

Thank you very much for your time.

Georgios


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