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MathGroup Archive 2000

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Re: NDSolve error message: Can't find starting value ...

  • To: mathgroup at smc.vnet.net
  • Subject: [mg23776] Re: NDSolve error message: Can't find starting value ...
  • From: Roland Franzius <Roland.Franzius at uos.de>
  • Date: Sat, 10 Jun 2000 02:59:22 -0400 (EDT)
  • References: <8hfggl$i4h@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Boundary values must be given for lower deriviatives than the highest.
Perhaps you mean R'[3]==R'[-3]==0 or R[3]==R[-3]==0?

Axel Kowald wrote:
> 
> Hello,
> 
> I try to solve the following second order ODE with NDSolve
> 
> NDSolve[{0 == R''[x] + DiracDelta[x] - R[x],         R''[-3] == 0,
> R''[3] == 0}, R, {x, -3, 3}]
> 
> and I get the following error message:
> 
> NDSolve::"ndsv": "Cannot find starting value for the variable x."
> 
> I couldn't find any description of this message in the Mathematica book, so I'm
> not sure what to do. I have a second order ODE with two boundary
> conditions, what's missing ?
> 
> Many thanks,
> 
>                Axel Kowald
> 
> P.S. Btw., this is done with Mathematica 4.

-- 
Dr. Roland Franzius
Theor. Physik FB Physik, Univ. Osnabrueck
tel ++49 +541 969 2683   fax ++49 +451 969 2670
  +++ exactly <<n>> lines of this message have value <<FALSE>> +++


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