Ventana software support forum

If you forget about the simultaneity and eliminate some conditions, the first equation simplifies to: "EXTRACTION RATE(Tpy)"=MIN( MINEABLE RESERVES*"1/year" , "TONS OF ORE MINING RATE(Tpy)"+"TONS OF STOCKPILE(Tpy)"+"TONS OF WASTE MINING RATE(Tpy)"+&q...

A diagram would help, too. It's not obvious why this should involve a simultaneity in the first place.

Can you post the model, or a submodel that illustrates the problem?

What exactly do you mean by "got no results"? Does the simulation generate a dataset? Does it have values for other variables? Are you using a savelist?

We've replicated the problem. We'll get a fix released ASAP.

Actually, I'd encourage you to seek help early, rather than wasting time trying to solve a problem that may have an existing answer. Also, if you don't, we never find out about these things.

What Windows version are you on?

I'd start with https://www.vensim.com/documentation/usr18.htm

A lot has changed since Dogan's paper, including the introduction of MCMC, which is the preferred way to do confidence bounds in many cases.
https://www.vensim.com/documentation/mcmc_sa.htm

Two options: - You can create a TIME BASE https://www.vensim.com/documentation/index.html?22120.htm https://www.vensim.com/documentation/fn_time_base.htm , and use that as the time axis https://www.vensim.com/documentation/index.html?timeaxis.htm . - You can use the date features of the time bounds ...

Great - that's what we like to hear!

Use Model>Export Dataset... - if you choose a sensitivity run, you will be asked whether you want to export the sensitivity results. They'll go to a tab-delimited file, but Excel can read that easily. The content of the file will be governed by the .lst file that you used when you ran the simulation...

The export options will be considerably enhanced in the forthcoming 6.4 release.

For the moment, you'll have to edit your .vpd file. If you have: *P product/1 just change it to *PF product/1 In 6.4 (release imminent) this will be integrated into the dialogs. Another option would be to create a special variable, like: final product = IF THEN ELSE( time < FINAL TIME, 0, product ) ...

I haven't looked at the model, but two thoughts: - It could be getting trapped in a local optimum. The Random Multistart option should take care of that, as long as there aren't too many. - Be aware that the payoff accumulates a flow. It doesn't measure the endpoint (unless you use the *PF option, w...

A continuous goal-seeking formulation like the one you describe will never reach 100% completion, because the goal achievement rate is always some fraction of the remaining gap, leaving a small fraction yet to do. For (EV- EV adopters)/POLICYTIMELINE, the time constant of the process is POLICYTIMELI...

I think, generically, your strategy could be something like: Phase a start = 3 Phase a duration = 4 Phase b start = INITIAL(Phase a start+phase a duration + TIME STEP) ~ time step is optional to prevent concurrence of a & b Phase b duration = 5 Phase a is started = STEP(1,Phase a start) Phase a ...

Good solution. The VECTOR operations are computationally expensive if you only need the min or max element.

You want VECTOR REORDER with SORT ORDER. See the example in https://www.vensim.com/documentation/fn ... eorder.htm

I think you want a stock subscripted by day, with a switch to indicate whether the day is still bookable. Something like: Day : (Aug 1 - Aug 31) Day Date = INITIAL(Day*One Day) {where one day is just to get the units straight} Flight is bookable[Day] = IF THEN ELSE( Time <= Day Date, 1, 0) Seats Boo...

You're on the right track; the only problem is that your lookup definition uses the subscript range name twice. If you want a different lookup for each element, you need to use the individual element names, like: MyRange : a, b MyLookup[a] [(2015,0)-(2020,4000)],(2015,1000),(2016,1500),(2017,2000),(...

Good thought. It's here: https://www.vensim.com/documentation/usr08.htm

Your workaround is correct. However, you have found a bug.

It's true that a flow with a non-constant expression can't be given a fixed initial value, but in your example the constant flow expression should be settable. I've put in a ticket for a fix.

Two options: To sample only the particular demand points you have, put them in a lookup, where the x-axis is the integer number of the point, like: Demand Lookup x: 1, 2, 3, 4, ..., N y: 32, 17, 39, 24, ..., 29 Then pick an integer and use that with the lookup: Demand Index = INTEGER( RANDOM UNIFORM...

See https://www.vensim.com/documentation/in ... ?22280.htm

You can ignore the warning, or suppress it by dividing time by a unit conversion factor (e.g., time/one year). Or, convert your lookup to time series data.

What if you follow the ASKYESNO with &SIMULATE>SETVAL|binary=1 ? Or use a checkbox control?

BTW the new build needed for this to work is now available (see top announcement).