topic Newbie: Not getting Integer values while running network flows in Mathematical Optimization, Discrete-Event Simulation, and OR

Newbie: Not getting Integer values while running network flows

nvidia39 — Thu, 04 Apr 2019 03:12:09 GMT

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;

Re: Newbie: Not getting Integer values while running network flows

RobPratt — Thu, 04 Apr 2019 03:49:25 GMT

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:

http://support.sas.com/documentation/cdl/en/ormplpug/68158/HTML/default/viewer.htm#ormplpug_netflow_sect159.htm

Re: Newbie: Not getting Integer values while running network flows

nvidia39 — Thu, 04 Apr 2019 12:14:18 GMT

Thank you so much for your response.

Another quick question, which SAS procedure is used for pure network flow?
Could you please share an example of the same?

Re: Newbie: Not getting Integer values while running network flows

RobPratt — Thu, 04 Apr 2019 14:35:24 GMT

SAS/OR: PROC OPTNET or the network solver in PROC OPTMODEL

SAS Optimization on SAS Viya: PROC OPTNETWORK or the network solver in PROC OPTMODEL

All those linked docs have lots of examples.