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RE: Using FindRoot in complex funtion
*To*: mathgroup at smc.vnet.net
*Subject*: [mg71936] RE: [mg71900] Using FindRoot in complex funtion
*From*: "David Park" <djmp at earthlink.net>
*Date*: Mon, 4 Dec 2006 06:39:31 -0500 (EST)
Raymond,
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},
Integrate[
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 earthlink.net
http://home.earthlink.net/~djmp/
From: tatsec [mailto:markelbbs at tom.com]
The program is :
dotnum=40;
sigma=Sqrt[2];
For[L=2,L<=dotnum,L=L+2,
FindRoot[Integrate[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}],{y,1}];]
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.
Raymond
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