Ventana software support forum

You might check the project model in the built-in help (User Guide, I think) for more ideas.

You can use the Stats tool if you just need to report these values. If you need them for use in an equation, you can use SAMPLE IF TRUE for the max. You can compute the average with a stock, or use a SMOOTH for a moving average. If you tell us a little more about what you're trying to do, we can sug...

Great. This is an interesting problem. I started to build a version of the model in Ventity, but concluded that it didn't confer a big advantage over Vensim's arrays (or at least I didn't immediately discover one). However, it is much easier to build a version with individual buildings as entities i...

You could run from -3500 to 0, and then use the Based On and Resume At options to start the run from 0 to 100: https://www.vensim.com/documentation/23320.htm This won't work if you have pipeline delays in the model. If that's an issue, there might be other options, though the internal delay states m...

You can make your decision rule a function of time, and search for the parameters, like: y = a + b*time + c*time^2 ... Or you can use VECTOR LOOKUP to search for an array of points over time. However, searching for a series of decisions over time is usually not a good strategy for realistic problems...

Since grinding is a destructive process, you may want to limit the number of times a part can pass through the rework stage. In that case, you might want something more like this:

The latest beta is #1254. Get it at http://ventity.biz. We've simplified the download process a bit, too.

One question: why the 500-element AaR dimension? Seems very big.

Mapping works in two cases: 1. same size arrays range : (r1-r10) previous : (r1-r9) next : (r2:r10) -> previous y[r1] = x[r1] y[next] = y[previous] + x[next] 2. few-to-many cities : MTcities, COcities MTcities : bozeman, helena COcities : denver, boulder state : MT, CO -> (cities : MTcities, COcitie...

Also, this might be a good Ventity model. You'd make each breeding stock with N failures an entity, and create the N needed entities automatically via an action.

I might do this the old-fashioned way, with an explicit chain of stocks rather than arrays. It might be a little more work to set up, but it's more visible.

What is the syntax for taking a partial sum of an array? I would expect something like SUM(array[i!],min_index,max_index) I avoid this kind of for-loop logic as much as possible. If the partial sum is over some predictable subset, use a subrange, e.g. range : a,b,c,d,e,f subrange : a, d, f y = SUM(...

For extraction: (Barrels/Well)/Year is mathematically equivalent to Barrels/(Well*Year). I think the only thing you need to do is set up an equivalence between "well" and "wells". https://www.vensim.com/documentation/ref_units_equiv.htm For Petroleum Reserves & Wells: You don...

TIME STEP applies to the whole model. The typical rule of thumb is that it should be <= to 1/2 of the shortest delay in the model.

In a stock-flow chain structure, units are the same throughout. So all stocks will have units of task, and all flows have units of task/time.

That's another .vgd editing topic. The syntax is here:
https://www.vensim.com/documentation/24010.htm
Let us know if you need help with the details.

Good to hear it. The latest is a look at model critique skills:
http://vensim.com/model-analysis-world-dynamics/

You might look through Chapter 17 of the User Guide, which covers arrays (subscripts). https://www.vensim.com/documentation/usr17.htm For #1, you need to write a separate equation for each element. https://www.vensim.com/documentation/21265.htm This might look like: Liklihood_of_widget_failure[f1]= ...

Generally this occurs from a typo. For example, if you have: range : a,b,c subrange : a,b but accidentally type subrange : a,d it's no longer clear what to do when subrange is not a subset of range. However, what you're getting seems different. I've never seen it. Can you save a model + spreadsheet ...

The answer depends on the type of the comparison variable. If it's a data variable (i.e. a variable that references data directly, with no equation) or a data equation (defined with :=) you can use: modelvar|datavar/weight Currently payoffs don't support comparison between model variables, so you ca...

Unfortunately this can't be done dynamically. Published models are essentially precompiled, because the .dll can't do that itself, so the array dimensions have to be fixed. GET XLS only updates the structure when run from the application. A possible workaround, if you need to add dimensions on the f...

BTW, the charting is slated for an upgrade (in progress).

That does sound wrong. I'll test.

Understood. Presumably there's a way to wrap C# for calling from C, but I don't know it. Writing small numerical modules in C is pretty straightforward - much easier than doing and performance will likely be better than with an extra layer and .net.

This is a Mac limitation. GET XLS uses GET DIRECT on the Mac, so the file has to be saved for changes to propagate. On Win GET XLS passes live values.

We've recently posted quite a few videos that introduce Ventity and work up to fairly complex models with dynamic creation of entities, cohorts and agents. See the links at http://ventity.biz/category/video/