I have been trying to run a network flow and get integer values for the flows.
Objective is to use generalized network as nodes L1, L2 has to be visited only once. However, I am unable to get integer values for the formulation. For some reason, interior point algorithm is triggered and not network simplex optimizer. I am not sure if I have used the right way to specify the lower and upper bounds. Please let me know if I am missing something.
/* _from_ = from node, _to_ = to node, _cost_ = cost to objective function, _mult_ = multiplier, _ lo_ = lower_bound , _up_ = upper_bound */ proc netflow arcdata = garcs nodedata = gnodes conout = gnetout source=A1 sink=COLLECT; capacity _up_; lo _lo_; mult _mult_; cost _cost_; run; data gnodes; infile datalines dlm="|"; input _node_ :$25. _sd_ :8.; datalines; A1|1 COLLECT|-3 ; run; /* _from_ = from node, _to_ = to node, _cost_ = cost to objective function, _mult_ = multiplier, _ lo_ = lower_bound , _up_ = upper_bound */ data garcs; infile datalines dlm="|"; input _from_ :$25. _to_ :$25. _cost_ :8. _mult_ :8. _lo_ :8. _up_ :8.; datalines; A1|L1T0|19|1|0|1 A1|L2T0|1|1|0|1 L1T0|L1T0P|0|2|0|1 L2T0|L2T0P|0|2|0|1 L1T0P|L1SUPER|0|1|0|1 L1T0P|L2T1|7|1|0|1 L2T0P|L2SUPER|0|1|0|1 L2T0P|L1T1|4|1|0|1 L1T1|L1T1P|0|2|0|1 L2T1|L2T1P|0|2|0|1 L1T1P|L1SUPER|0|1|0|1 L2T1P|L2SUPER|0|1|0|1 L1T1P|A1SINK|116|1|0|1 L2T1P|A1SINK|95|1|0|1 L1SUPER|COLLECT|0|1|0|1 L2SUPER|COLLECT|0|1|0|1 A1SINK|COLLECT|0|1|0|1 ; run;
Generalized network flow problems do not have the integrality property, so there might not be an optimal solution that takes only integer values. Also, PROC NETFLOW is a legacy procedure that is no longer documented. The SAS/OR 14.1 documentation provides an example that illustrates how to solve a generalized network flow problem with PROC OPTMODEL:
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