variable initial value in NDSolve

*To*: mathgroup at smc.vnet.net*Subject*: [mg99123] variable initial value in NDSolve*From*: Stef <ste.peer at gmail.com>*Date*: Tue, 28 Apr 2009 04:42:27 -0400 (EDT)

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!