Ventana software support forum

Greetings!

I would like to know is there any chance in vensim optimization to have the result during time?
for example I made a simple model to learn vensim optimization. in this model I have three suppliers which I want to allocate order amount to them without using (ALLOC function ). now I want to optimize the amount of orders allocated to each supplier to minimize cost for example. however I expect to see the result as the optimal amounts for each supplier BASED OF TIME. is there any help or advice you can give me?

Cheers
Samira

You can make your decision rule a function of time, and search for the parameters, like:

y = a + b*time + c*time^2 ...

Or you can use VECTOR LOOKUP to search for an array of points over time.

However, searching for a series of decisions over time is usually not a good strategy for realistic problems. Such an open loop rule can be a useful test, but it won't give you any insight about model structure, and it's completely useless as soon as the state of the system changes from what was optimized.

What you really want is to construct a feedback decision rule that leads to time-varying decisions, then find parameters for the rule that perform well and are robust to a variety of conditions.

Hi Tomfid

Thanks for your reply. I couldn't solve the problem even I made it worse, I used subscripts for my decision variables and now the optimization is not working anymore. Could you please have a look to my sample model( I tried to make a simple one just to learn Vensim through it).
it would be very grateful if you could help me with making a sample vector look up for Suppliers' order amount in the model and help me to run the optimization based on time in the model.

I have attached the file in here.

Cheers
Samira

You'll need to attach the .voc and .vpd files for a diagnosis.

If a variable is subscripted in the model, it must also be subscripted in the control files.

Sorry, I have attached them.
Thanks for your time and consideration.

For subscripts I selected them all in subscript control. Is it what you mean?

You need to specify:
0<=suppliers' Order Amount[supplier]<=70000

Thanks Tomfid for your help.