Originally posted by: xinzhangandy

hello everyone, I meet a problem when I try to solve a OD network, I can not express the outward neighbour and inward neighbour of  node i. The constraint is as follows:

Wish someone can give me some idea or tell me if there is an example in Cplex about this to learn.

Hi,

have you looked at the example in CPLEX_Studio129\opl\examples\opl\models\Netflow ?

You will see

subject to {
   // Preserve flows at each node.  Note the use of slicing
   forall (i in Nodes)
     ctNodeFlow:
      sum (<i,j,c,ub> in Arcs) Flow[<i,j,c,ub>]
    - sum (<j,i,c,ub> in Arcs) Flow[<j,i,c,ub>] == SupDem[i];
}

regards

Originally posted by: xinzhangandy

Yes, this is what I want, thank  you for your help all the time. Have a nice day