Ventana software support forum

Dear forum members,

I tried developing a model which has a feedback loop. As it was showing simultaneous equations error, I tried using SIMULTANEOUS function. Then it started showing 'Unable to Converge Simultaneous Equations at Time t error'. In order to avoid that I converted one of the variable in the loop to a level as it was mentioned in one of the answers, but the error still continues. Can you please help me with this.

Thanks and Regards,
Sankeerthana.

You will need to upload the model for us to take a look at it.

I herewith attach the model.

Thanks and Regards,
Sankeerthana.

I think the simultaneity here signals a conceptual issue, which would be revealed if you completed the definition and checking of units.

The basic problem is that net farm income is presumably denominated in money, and therefore can't possibly be connected by flows to the rest of the stock-flow structure, which has units of physical water it appears.

Actually, I guess you have implicit units conversions in the integration equations. This may be technically OK but is usually confusing for users. Probably better to have 2 or 3 distinct stock-flow structures: one for water, one for crops and one for money.

As it is now defined, net income appears to be a flow concept, not a stock concept.

I think you want something more like this:

Thank you so much.

Regards,
Sankeerthana.

I forgot to mention one other item: I think "profit spent on irrigation" and "irrigation cost" might be conceptually the same thing?

Yeah I guess. I will convert it into one variable. Thank you.

Regards,
Sankeerthana.