Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2006
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2006

[Date Index] [Thread Index] [Author Index]

Search the Archive

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



  • Prev by Date: Re: Solving the Cubic
  • Next by Date: Re: Problem with Minimize function
  • Previous by thread: Using FindRoot in complex funtion
  • Next by thread: Re: Using FindRoot in complex funtion