Vensim DSS Reproducible Crash Bug

[jrissman]

On further investigation, it does have to do with the widths (the standard deviations of the bell curves).

For ships, rail, and aircraft, we don't distinguish them by technology type (as we do for on-road vehicle modes). 100% of them get allocated to the "nonroad vehicle" technology type. Since we only have one recipient for these technologies, the width of the priority curve was unimportant, so I used a default value of $1. That worked fine in Vensim 6.4E.

However, Vensim 7.0 fails to allocate anything unless the width is of a similar magnitude as the priority. When I changed the width for aircraft to $10,000,000 it allocates them correctly.

I'm going to increase the widths on the other vehicle types to be in the ballpark of the priorities, then see if that fixes the allocation problem here and if it fixes the crash bug in earlier versions of Vensim.

[jrissman]

Adjusting the widths to be similar in magnitude to the priorities fixes the allocation problem in Vensim 7.0. It does not fix the crash bug in Vensim v6.3G. So the two issues are unrelated.

Therefore, I guess we're at the point where everything is working in Vensim 7.0, but not in the versions earlier than 6.4D or 6.4E (it's not clear which). So we need to upgrade the Linux multi-context version to Vensim 7.0. I'll be in touch by email about that.

[Administrator]

I've found the issue with the different calculations (we added an additional check (which should only be in extreme circumstances) to the ALLOCATE function in 7.0 and it's had a knock on effect). I've removed it, so the 7.1 build will be back to the old calculations.

I'll be in touch via email later today when I've got a build ready.

[jrissman]

I can confirm that Vensim 7.1 allows allocation to work correctly even when the widths are significantly smaller than the priorities. (Also, like Vensim 7.0, it does not crash upon using the "Simulate" button on EPS 1.3.0.) So as far as I can tell, Vensim 7.1 addresses all known issues regarding the compatibility of Vensim and EPS 1.3.0.