Rob
Thank you very much I will use the updated code and let you know. I will also add the proportion. Will work on the full fledged model and let you know of any issues. The one question i have is on how my point (c) in my earlier comment. How do I write the impvar and constraints correctly? Example : impvar like "PerBox_Based_Costs_CFS" and constraints like "BoxConCFS" in my code, because in your code there is no need of i in ISN, but in the full fledged model, capacity or rate is a function of Org, Des, MOL, Box , T1 and T2. Without i in ISN, i would like to learn how to write the constraints and impvar correctly.
Thanks a ton for all your support as always.
I made one more correction to RationalVendor in the toy code, and the new optimal solution has objective value $4304, with both V1 and V2 using CYS. Note that for the $3622 solution in your spreadsheet, vendor V2 does not behave rationally because the CYS cost is $1050 < $1145, so V2 would instead choose CYS. On the other hand, $3622 is still the correct optimal objective value if the vendors cooperate.
Regarding your question (c), I think this is what you want:
impvar PerBox_Based_Costs_CFS {w in T2} = sum {b in BOX} PerBox_Based_Rate_CFS[b,w] * BoxesNeeded_CFS[b,w];
impvar TotalVol {m in MOL, w in T2} = sum {i in ISN} Volume_ISN[i] * Is_ISN_Mol[i,m,w];
con BoxConCFS {w in T2}: sum {b in BOX} Volume_Capacity_CFS[b,w] * BoxesNeeded_CFS[b,w] >= TotalVol['CFS',w];
Rob
This is a very quick syntax question. To your toy code, I have this one. There is a minimum charge to volbased cost. If Volbased cost >Min then Volbased cost else Min . I get syntax errors. Can you tell me what is the correct way?
num volRate_Min{MOL} = [0 75];
for {i in ISN,m in MOL} do;
if VolBasedCost[i] > volRate_Min[m] then fix VolBasedCost[i]=VolBasedCost[i];
else fix VolBasedCost[i] = volRate_Min[m];
end;
You cannot fix an implicit variable, and you can fix a variable only to a constant. Instead you can modify the IMPVAR statement as follows:
/* impvar VolBasedCost {i in ISN} = Volume_ISN[i] * sum {m in MOL} volRate[m] * IsMol[i,m];*/
impvar VolBasedCost {i in ISN} = sum {m in MOL} max(Volume_ISN[i] * volRate[m], volRate_Min[m]) * IsMol[i,m];
Because of the OneMol constraint, each i will have IsMol[i,m] = 1 for exactly one m. The new IMPVAR declaration will enforce VolBasedCost[i] to be the larger of Volume_ISN[i] * volRate[m] and volRate_Min[m] for that m.
Rob
Thank you. This is perfect.
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