I've been busy with a model, but I'm uncomfortable about the result because I think GAMS violates a constraint. What I want to tell to GAMS is:
"check demand first -> then check current stocks -> **IF** there is enough stocks sell from current stocks -> **IF** there is **not** enough stocks first buy (produce) then sell."

I think in the model GAMS does not obey any demand (sell), any minimum values and sells everything without buying any.

The model is hereinbelow:

```
Sets
i items /s,p,b/
t time in quarters /1,2,3/
Parameters
price(i) selling price per unit i per quarter in euros /s 6.34, p 6.46, b 5.93/
inistock(i) initial stock in units /s 320000, p 296199, b 104208/
cap(i) capacity limit for each unit /s 400000, p 350000, b 150000/
c cost of holding 1 unit of i /s 10, p 15, b 12/
Scalars
tcap total capacity of warehouse /650000/
Variables
stock(i,t) stock stored at time t
sell(i,t) stock sold at time t
buy(i,t) stock bought at time t
cost total cost
Positive Variables stock,sell,buy
Equations
cst total cost occurs
stck(i,t) stock balance of unit i at time t;
cst.. cost=e=sum((i,t),price(i)*(buy(i,t)-sell(i,t))+c(i)*stock(i,t));
stck(i,t).. stock(i,t)=e=inistock(i)+stock(i,t-1)+buy(i,t)-sell(i,t);
stck.up(i,t)=tcap;
Option LP=Cplex ;
Option optcr=0;
Model TWH The Warehouse Problem / all /;
Solve TWH minimizing cost using lp;
```

Thank you in advance for your support!

asked
**02 Sep '16, 04:53**

dregazz

11●1

accept rate:
0%