Ventana software support forum

Thanks. This sounds like a cool model, due to the real options angle - sell all the tickets up front and guarantee revenue? Or hold some for later in the season, and take your chances on the ups and downs of performance? Good luck with the model.

Also http://www.vensim.com/documentation/timeboundsdates.htm

1) from Little's Law, the average residence time in a stock is (stock/outflow). If you need more disequilibrium detail, you can create an explicit coflow to keep track of accumulating time. I think there have been a couple threads here on the topic. Something like http://www.ventanasystems.co.uk/for...

Just in case you haven't discovered it, you can build up subscripts hierarchically, which might make the 1-dimension idea easier:

For many situations, though, multiple IF THEN ELSE statements, and similar discrete logic, should be avoided.

EXCEPT statements are fixed. For some purposes, VECTOR SELECT might work for you (it doesn't execute elements that are 0 in the select statement). Or you might be able to use GET XLS SUBS.

Also some of the models in the User Guide might be relevant - I'm thinking of the Yeast example, but there are probably others.

Presumably there are thousands of tickets for any one game? Probably the one thing you wouldn't want to do is model literal individual tickets. Ventity isn't optimized for millions of lightweight entities with no dynamics, and I'm not sure it makes sense anyway. However, I think two aspects of this ...

Since your model has few parameters, you can probably fit it pretty well without using the optimizer. First you need to get your data into the model so that you can plot it alongside the simulation output. See http://www.vensim.com/documentation/usr16.htm . Since your data is in Excel, GET XLS or GE...

I agree that SI prefixes should simply be known by the software. It should also understand compound units, e.g. a Newton is a kg/m/s/s. It's in the Ventity spec, partially implemented. (More about that tomorrow.) One user question is how far to go with automatic conversion (as in the Mathematica exa...

Also, if this is a financial calculation, see: http://www.vensim.com/documentation/fn_financial.htm

Is the result from vensim_command("SPECIAL>LOADMODEL|worldapp.vpm") a 0 or 1?

What makes you think it's not loaded? Getting a 0 from check_status after a LOADMODEL could be normal.

What if you call vensim_get_info with 5 for the current model name? Or issue a MENU>RUN|o command?

When you get an FP error, take note of the warning at runtime: ERROR: Floating point error computing - #Current Completion Date>SMOOTHI# - at time = 0.000000. Then use the table tool to look at the problem variable and its inputs: Time (Month) 0 "Current Completion Date" and its causes Run...

Project management models cry out for arrays, so in the future you'll want to consider Pro or DSS. However, starting simple is always good.

There are a number of recent threads on a project model here; if you look through those, there are several links to useful theses and papers.

There isn't an option to directly suppress the y axis scale, but you could use the :y-label keyword: http://www.vensim.com/documentation/24000.htm You'd have to do this in a text editor on a .vgd file though.

Unfortunately I don't have anything to add. We'd need a 2-dimensional subscript picker for such combinations. I'm not sure how to implement that in the interface. We have the same problem in Ventity, so perhaps we'll come up with a solution that's portable.

A comment on your draft structure in the attachment: The stock-flow structure shown, sched completion date -------- Adjusting -------> actual completion date implies that the Adjusting flow reduces the scheduled completion date when it increases the actual completion date. This is not a situation wh...

Here's an example of the kind of structure you might want. It would need some tweaking - for example, it doesn't handle the time after the project is complete appropriately (it keeps adjusting the schedule). Also the task workflow portion is greatly simplified.

The FIND MARKET PRICE function provides a lot of flexibility in the supply curve descriptions. If you want supply curves that are arbitrary functions or lookups, you could accomplish the same thing by using FIND ZERO to clear the market. Finding a general solution for arbitrary demand curves isn't r...

Yes - it's easy:
http://www.vensim.com/documentation/editmenusketch.htm

I'm not sure where the threshold is with respect to speed, but that's of no interest unless your model is slow already.

Of greater importance is that, if your selection matrix is constant, causal tracing with VECTOR SELECT will show only elements that are used, rather than a lot of useless 0s.

Steady state error = in equilibrium, actual workforce (cumulative workforce level) doesn't equal required workforce. If you simplify to a first order (one stock model), it's easy to see why this happens: workforce = INTEG( hiring - departing, initial workforce ) hiring = (desired workforce - workfor...

Take a look at http://vensim.com/causal-tracing-in-vensim/ , then revisit your model. The aggregate behavior looks pretty reasonable to me, as long as willingness to increase workforce = 1. There's some steady state error (equilibrium workforce is short .3 people), because the hiring decision doesn'...

There are two ways to isolate: - copy/paste the structure into a separate model, improve it until you are satisfied, then copy/paste back into the complete model, or - break the causal links between the elements of the integrated model temporarily One way to implement the second approach might be: {...