Ventana software support forum

Hi Team,

Hope everyone is doing great.

I would like to ask regarding on the same old error as posted previously by other members.
Tried to go through all of the solutions from previous posts, but still couldn't get the idea on how to solve my issue.

My model faced the "simultaneous equations involving :......" error as shown below. I have tried the ACTIVE INITIAL solution, but it didn't work with my model.
Attached is my model. I really hope that i could get any help from you guys.

Thanks in advance.

You've got some conceptual problems with the model.

"New installed cap" should really be a level, it goes up when you add capacity, goes down when you remove capacity. Similar structure for the population you have in the model.

Similarly, your demand should not be diagrammed as a stock-flow system (the equations might be OK).

tomfid wrote: ↑Thu Jul 16, 2020 7:24 pm Similarly, your demand should not be diagrammed as a stock-flow system (the equations might be OK).

What would you suggest?

If demand = a*pop + b*GDP, then it should be an auxiliary (no box, no inflow).

tomfid wrote: ↑Fri Jul 17, 2020 1:31 am If demand = a*pop + b*GDP, then it should be an auxiliary (no box, no inflow).

Changed it according to your suggestion. Thanks a lot, Tom

Similarly, on your second page, you're using boxes for visual emphasis. This is fine, but it limits your ability to communicate with anyone who's expecting the System Dynamics convention, boxes = stocks.

tomfid wrote: ↑Fri Jul 17, 2020 3:34 pm Similarly, on your second page, you're using boxes for visual emphasis. This is fine, but it limits your ability to communicate with anyone who's expecting the System Dynamics convention, boxes = stocks.

Yup, i did that just for the sake of visual. Thanks anyway for suggestion, Tom.

Anyway Tom, i have posted one question in another thread. I would love to hear a solution from you.