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Re: variable initial value in NDSolve

  • To: mathgroup at smc.vnet.net
  • Subject: [mg99162] Re: variable initial value in NDSolve
  • From: dh <dh at metrohm.com>
  • Date: Wed, 29 Apr 2009 03:48:22 -0400 (EDT)
  • References: <gt6fgd$rli$1@smc.vnet.net>


Hi Stef,

if you want a decent answer, you should give a working simple example.

Well, why should R[tstart] go to infinity, you say: R[tstart]=0 (note 

that there is an error it should read == not =).

Do you have a discrete System???

Daniel



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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