Simultaneous loop error

[Danny]

Dear Forum member,

My model gives me the following error: Unable to converge simultaneous loop at time …
What does it mean? It is not all the time, only for some time steps.
Please help me.

Thanks, Danny

[Administrator]

It sounds like you are you using the SIMULTANEOUS or FIND ZERO functions.

If using SIMULTANEOUS, Vensim tries running around the loop until nothing in the loop changes any more. Could this be the problem you have?

More details on SIMULTANEOUS are here
http://www.vensim.com/documentation/html/22260.htm

Tony.

[Danny]

Thank you Tony,
I suppose this is my problem. I will try to find another solution than SIMULTANEOUS.

Danny

[bob@vensim.com]

If you can reformulate to use FIND ZERO (sometimes that reformulation is tricky) you will likely get better results. Another alternative is to try to set something analogous to TIME STEP in the simultaneous loop - see for example "Pg Adj Frac" in the NEP4SIMUL model that ships with Vensim.

[sankee82]

Can you please elaborate what do you mean by something analogous to timestep?

[Administrator]

It might be better if you started a new thread on your problem, this discussion is over 10 years old.

[tomfid]

Check the sample model referenced above - typically located in C:\Users\Public\Vensim\Models\Sample\EXTRA