How is a conditional summation possible in Cplex? like sumifs in Excel?

Question

I want to sum all used resources among times in my model (it\'s rcpsp model) how can I do it in CPLEX? at first I wrote this:

forall(k in K)
  forall(t in 1..f[n         


        

Answer 1

You can use dexpr for manipulating decision variables. Here is an example from the same resource IBM Knowledge Center.

Without dexpr

dvar int x in 0..20;
dvar int y in 0..20;
dvar int d;
dvar int s;
maximize (d);
subject to {
  d==x-y;
  s==x+y;
  s<=15;
  s<=x-2*y;
  d>=2;
  d<=y+8;
  1<=d;
}

With dexpr

dvar int x in 0..20;
dvar int y in 0..20;
dexpr int d=x-y;
dexpr int s=x+y;
maximize (d);
subject to {
  s<=15;
  s<=x-2*y;
  d>=2;
  d<=y+8;
  1<=d;
}