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Re: variable initial value in NDSolve

  • To: mathgroup at
  • Subject: [mg99191] Re: variable initial value in NDSolve
  • From: Jens-Peer Kuska <kuska at>
  • Date: Wed, 29 Apr 2009 06:38:56 -0400 (EDT)
  • Organization: Uni Leipzig
  • References: <gt6fgd$rli$>
  • Reply-to: kuska at


and you are sure thay ou have not missed some equations ?
One initial condition for ec[t] and a differential equation for
R[t] ? And you are sure that you have not mixed up Equal[] (==)and
Set[] (=) ...


Stef wrote:
> Dear Mathematica community,
> I am pretty new with using Mathematica. So, maybe there is a very
> obvious solution to my problem that I missed to find out myself.
> I am trying to solve a problem that is setup like that:
> The cost function ec[t] depends on cumulative arrivals R[t]. At a
> variable starting point tstart (for which i try to find a cost-
> minimizing value in a NMinimize fct), cumulative arrivals are 0.
> NDSolve[{ec'[t]==0,R[tstart]=0}, R[t],t]
> But obviously, the derivative of R[tstart] goes to infinity, which is
> why no solution can be found.
> Thanks for helpful comments!

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