Ventana software support forum

Transposing is easy - just do something like:

y[a,b] = x[b,a]

If you want the value in the immediately previous time step, you can store it in a stock, or use DELAY FIXED with a lag of TIME STEP. SMOOTH works too, as long as you're using Euler integration.

Could you encode the string information as numbers, or are they ad hoc and numerous?

Also, check the help - there's a sample model attached to the VECTOR SORT topic in the manual.

You can't initialize the internal state of a queue with that level of detail. How many sheep do you have? An array of individuals might be a viable alternative. (If you have a lot, Ventity might be even better.) For your inventory-age-labor example, that sounds like a classic aging chain, which coul...

Cool. When I first wrote the code, I had at least two ambitions that remain unrealized: - use the LP infrastructure to create some custom allocation functions. For example, the LP makes it easy to solve the many-to-many noncommodity allocation problem, with unique costs (e.g. shipping) for each supp...

I think the external lib may need to be complied with the flag DPMATH so that it's variable types are compatible with DP Vensim. I don't recall the details, but I'm hoping Tony does.

We're happy to supply a quote if you need it.

It actually is technically possible to create a client-side .dll for several platforms (Win, Mac, Linux, iOS); we don't have off-the-shelf licensing for those but could discuss it.

The latest beta is #E30, September 27th. Get it at http://vensim.com/ventity-beta/ . We're preparing for commercial release, so this version is testing licensing infrastructure. For the moment, this could hardly be easier - just click the "Continue Evaluation" button when you start up the ...

Can you post or email us the model? It might just be size, not be a platform issue.

The reason you can't retrieve values of variables ahead of time in Vensim is that this creates an acausal model. No one can really look into the future; they have expectations of the future, not knowledge. Normally the right way to solve the problem is to model those expectations explicitly. If you ...

How have you changed the time parameters? If you use Model>Settings, you're changing the model. You can make runtime changes with via the various constant setting methods. For reuse, I would normally put the modified values in a .cin file that could be loaded as needed.

Create an array dimension for the projects, and use SUM(value[project!]) to add them up. https://www.vensim.com/documentation/fn_sum.htm Set the value to 0 for projects that are inactive. If you're not familiar with declarative languages like Vensim, you should probably work through the User Guide, ...

There have been several recent threads on this. See http://www.ventanasystems.co.uk/forum/viewtopic.php?f=2&t=6388&p=22779&hilit=VECTOR+LOOKUP#p22779 and http://www.ventanasystems.co.uk/forum/viewtopic.php?f=2&t=6349 The optimizer only works on constants; you can use VECTOR LOOKUP to...

average x = SMOOTH(x,interval) gives an exponentially weighted moving average of x with mean horizon of interval.

If you need 0s in between, you can use something like:

avg or 0 = IF THEN ELSE( PULSE TRAIN(initial time, time step, interval, final time), average x, 0 )

The PULSE TRAIN(INITIAL TIME, TIME STEP, SAVEPER, FINAL TIME) creates a signal variable that is zero most of the time, and 1 at intervals equal to SAVEPER (assuming that SAVEPER=500). If you also want to capture a value only when IRE > 1, you can just add that to the condition with :AND:.

You could use SAMPLE IF TRUE to sample the value of the variable every 500 units. Something like:

saved x = SAMPLE IF TRUE( PULSE TRAIN(INITIAL TIME, TIME STEP, SAVEPER, FINAL TIME), actual x, actual x )

This turns out to be quite tricky. I ran the model with 5 and 10 year cohorts, and got quite different results. The difference emerges with births from the earliest created cohorts (not the preexisting ones in the data). Here's the sum of births: births.png The difference arises from the timing of t...

I think the answer probably has to do with the granularity of the input data, but I'll have to fire it up and take a look to be sure.

If you're using Grid with VECTOR, order won't matter, because the setup is nonrandom. The order of the simulations might vary, but the same set will be run. Exporting the run to view the data directly is a good check. Documentation is here https://www.vensim.com/documentation/sensitivity.htm Every d...

For the Max, see the first example in https://www.vensim.com/documentation/fn_sample_if_true.htm Also: http://www.ventanasystems.co.uk/forum/viewtopic.php?f=2&t=6366&hilit=SAMPLE+IF+TRUE For the moving average, you can build a structure like: average X = Sum X / Averaging Period Units: stuff...

You need to specify:
0<=suppliers' Order Amount[supplier]<=70000

That's the special value for :NA:. https://www.vensim.com/documentation/index.html?na.htm

The largest ordinary value is about +/- 3 x 10^38.

In double precision Vensim DSS the largest value is about 2 x 10^308.

Can you post a sample model?

Have you tried double precision Vensim DSS?

You'll need to attach the .voc and .vpd files for a diagnosis.

If a variable is subscripted in the model, it must also be subscripted in the control files.