Ventana software support forum

The issue seems to be that when you leave off a stock from the kalman.prm file, Vensim assumes the initial Var for that stock to be 1, and the driving noise var to be 1e-6 (this is based on a quick comparison on a simple model like the above). I don't know if this assumption is well documented in th...

All, I am trying to figure out how to build external functions to work with Vensim. Not being a programmer I rely on AI (claude or chatgpt) to get the project together, but I have not been able to succeed so far. Are the examples of external functions shipped with Vensim up-to-date and usable with v...

Thanks so much Alireza; that initial value was not needed and removing it indeed solved the problem!

Hi, In simulating the attached model I get weird behaviors, where some 'Initial' variables are simulated incorrectly (and I get warnings for Active/Initial difference). Specifically, check out: 1- 'Sum Initial Buildings' vs. 'Desired Current Buildings' at time zero. The two should be the same but th...

Thanks. I will try scrapping the online version.

Hi,
For my SD course I want to feed Vensim manual to an LLM support engine to respond to student questions on Vensim. However I don't seem to find any pdf of the manual, or any way to easily download the online manual quickly. Any suggestions?
Thanks,
hazhir

Thank you Travis and JJ for thoughtful comments.
Travis, the SDEverywhere functionalities you note (and some of which I had seen a while back in your talk) are really helpful, and any additional documentation/demo/seminar to enable regular users to benefit from those would be a great step.

Great thoughts and suggestions, thank you!

Dear All, I am starting a new project that would include many iterations and adjustments of a complex model over coming months and need tools to ensure changes are not breaking other parts of the model, likely using an automated suite of tests. I am wondering about the value of Vensim's built in rea...

Thanks, that would be great. In the meantime, I found a recent SDR paper by George Backus does a lot of what one may need without going the LP/optimization route, here is the link for those interested: https://onlinelibrary.wiley.com/doi/10.1002/sdr.1744?af=R The Vensim implementation is well docume...

Thanks Tom. An LP function built into Vensim could go a long way towards solving a lot of different problems, could that be on the development path? Absent that, would building an external function to do LP that comes packaged in the example external function with Vensim installation be a feasible l...

Thanks Tom. Will reach out directly for example. The computational costs are probably OK for 5 and find zero, but may become problematic when subscripted over multiple regions each with its own allocation, and doing calibration runs. Any way we can use vector elm map to calculate later subscripts ba...

Hi, I am trying to solve a many to many allocation problem with heterogenous preferences. Specifically, the matching between positions (lets call it demand) and labor (supply), with both subscripted based on education (e.g. five categories spanning primary to higher graduate). We have supply and dem...