Ventana software support forum

Was trying to model Jay Forrester's market growth model and ran into a simultaneous equations error.

Essentially - this was on 'desired capacity'. If desired capacity is a floating goal vis-a-vis actual capacity, then I was not able to initialize desired capacity.

Vensim gave me a simultaneous equations error. Looking up at the manual, I reformulated the equation for desired capacity and it worked ok.

But, is there a way to solve this problem without using the 'SIMULTANEOUS' function?

Model is attached - Its not complete, and only two of the sectors have been done in it so far.

Thanks
Malli

You need to see how this was originally formulated. It is possible Jay simply used a number as you have. In general for formulating initial condition it is good to try to put things into some sort of equilibrium or steady state - though for this model that does not really make sense. My recommendation if you do not want to follow Jay directly would be to put in the constant initial capacity.

Hi Bob,

Thanks. Went with the constant initial capacity