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MathGroup Archive 2006

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RE: Using FindRoot in complex funtion

  • To: mathgroup at
  • Subject: [mg71936] RE: [mg71900] Using FindRoot in complex funtion
  • From: "David Park" <djmp at>
  • Date: Mon, 4 Dec 2006 06:39:31 -0500 (EST)


Do you mean Pi instead of pi?

Why don't you try evaluating the integral for some L cases before you plug
it into FindRoot? When I tried to evaluate some of the integrals, they
didn't converge because of the singularity at zero.

f[2] = With[{sigma = Sqrt[2], L = 2},
      2^(1/2 - L/2)*sigma^(-1 - L)*(Abs[t])^(1/2*(-1 - L))*
        BesselK[(1 - L)/2, Abs[t]/sigma]/(Sqrt[Pi]*Gamma[L/2]), {t, 0, y}]]
with the error message...
\!\(Integrate::"\<idiv\>" : \*"\"\<Integral of \
\!\(\[ExponentialE]\^\(-\(Abs[t]\/\@2\)\)\/Abs[t]\^2\) does not converge on
\!\(0, y\)}.\>\""\)

David Park
djmp at

From: tatsec [mailto:markelbbs at]

The program is :


when L<30, FindRoot can find the root of function.but L=>30,FindRoot
can't calculation.So How to solve this problem?
Thanks in advance for any help you can give me.


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