What error are you seeing?
I'm guessing that you're putting varname[range] in the headers. I don't think that works - you need to provide a separate column for each varname[element].
Search found 3800 matches
- Fri Aug 25, 2023 2:24 pm
- Forum: Vensim
- Topic: Sensitivity analysis using the file option in a subscripted model
- Replies: 13
- Views: 705
- Thu Aug 17, 2023 5:46 pm
- Forum: Ventity
- Topic: Entity activation time
- Replies: 5
- Views: 1820
Re: Entity activation time
We can get you a nightly build when the fix is included.Just walked through with the debugger.
The first try fails due to loading sequence and issues the error message too soon. The automatic retry works. The bug is that the error message is wrong -- there is not a real problem.
- Thu Aug 17, 2023 4:12 pm
- Forum: Vensim
- Topic: unit consistency bug
- Replies: 5
- Views: 1894
Re: unit consistency bug
Actually, the problem with "miles per trip" is that the equation is constant, but the diagram includes a link from "attractiveness of driving" so the equation is invalid (inconsistent with diagram). We should probably upgrade the warnings to distinguish missing equations from mis...
- Thu Aug 17, 2023 4:05 pm
- Forum: Vensim
- Topic: unit consistency bug
- Replies: 5
- Views: 1894
Re: unit consistency bug
The others are either correct warnings, or Vensim cannot check as there is no equation to check against. Not so. "miles per trip" is a constant =20 and has unit mile/trip, but it's still reported as an error (no units). I suspect that the parsed model is so incomplete that Vensim fails to...
- Wed Aug 16, 2023 1:56 pm
- Forum: Ventity
- Topic: any plans for a Mac version of Ventity?
- Replies: 3
- Views: 1956
Re: any plans for a Mac version of Ventity?
[ ] Almost done.
[ ] In the works.
[ X ] We're thinking about it
[ ] It's complicated.
[ ] No way, don't hold your breath
"Don't hold your breath" might still be good advice.
[ ] In the works.
[ X ] We're thinking about it
[ ] It's complicated.
[ ] No way, don't hold your breath
"Don't hold your breath" might still be good advice.
- Wed Aug 16, 2023 1:55 pm
- Forum: Ventity
- Topic: any plans for a Mac version of Ventity?
- Replies: 3
- Views: 1956
Re: any plans for a Mac version of Ventity?
[ ] Almost done.
[ ] In the works.
[ X ] We're thinking about it
[ ] It's complicated.
[ ] No way, don't hold your breath
"Don't hold your breath" might still be good advice.
[ ] In the works.
[ X ] We're thinking about it
[ ] It's complicated.
[ ] No way, don't hold your breath
"Don't hold your breath" might still be good advice.
- Wed Aug 16, 2023 12:18 am
- Forum: Ventity
- Topic: Entity activation time
- Replies: 5
- Views: 1820
Re: Entity activation time
The HG B/D mixup looks like a bug to me. Checking with the devs.
However, it's not clear to me that compound keys are needed here, at least for S1. Every S1 Factory is unique, so the group isn't needed to find the factory.
However, it's not clear to me that compound keys are needed here, at least for S1. Every S1 Factory is unique, so the group isn't needed to find the factory.
- Wed Aug 16, 2023 12:08 am
- Forum: Ventity
- Topic: Entity activation time
- Replies: 5
- Views: 1820
Re: Entity activation time
I'll take a look.
- Mon Aug 14, 2023 5:11 pm
- Forum: Vensim
- Topic: Help with a sigmoidal behaviour in a stock variable
- Replies: 3
- Views: 554
Re: Help with a sigmoidal behaviour in a stock variable
Sounds like what you want is a logistic growth model. The model here https://vensim.com/vensim-video-library/#Introduction_to_System_Dynamics_With_Vensim has a variant of that near the 1hr mark, particularly if you make the product lifetime very long so that there's effectively no outflow from custo...
- Tue Aug 08, 2023 9:57 pm
- Forum: Vensim
- Topic: Units Check whack-a-mole
- Replies: 9
- Views: 1098
Re: Units Check whack-a-mole
Ventity licensing will be changing to look more like Vensim. In the meantime, we'll include a license with a Pub Rsch Vensim Pro license (email us at info at ventity.biz if it doesn't happen automatically).
- Mon Jul 31, 2023 7:19 pm
- Forum: Vensim
- Topic: how do I reload an existing dataset, including variable values?
- Replies: 5
- Views: 540
- Mon Jul 31, 2023 6:14 pm
- Forum: Vensim
- Topic: how do I reload an existing dataset, including variable values?
- Replies: 5
- Views: 540
Re: how do I reload an existing dataset, including variable values?
If you change variable values interactively, e.g. by moving sliders, the model always retains the underlying equation values as a default. If you change the equations, you have to manually change back. More advanced versions of Vensim can save and load change files (.cin) during simulations, to make...
- Mon Jul 31, 2023 6:07 pm
- Forum: Vensim
- Topic: Units Check whack-a-mole
- Replies: 9
- Views: 1098
Re: Units Check whack-a-mole
After a closer look, my conclusion is that the model is kind of bonkers. Normally units prevent conceptual errors like mixing up stocks and flows, but in this case I think the general difficulty in defining units is a big red flag in itself. It means that the model is rather far from an operational ...
- Mon Jul 31, 2023 4:36 pm
- Forum: Vensim
- Topic: Model calibration in Vensim PLE
- Replies: 2
- Views: 506
Re: Model calibration in Vensim PLE
No - PLE is really targeted at learning about dynamics.
- Sun Jul 30, 2023 7:25 pm
- Forum: Vensim
- Topic: how do I reload an existing dataset, including variable values?
- Replies: 5
- Views: 540
Re: how do I reload an existing dataset, including variable values?
Rather than editing equations, you probably want to make your changes to the model live, in Synthesim, or using change files.
- Sun Jul 30, 2023 1:10 am
- Forum: Vensim
- Topic: Units Check whack-a-mole
- Replies: 9
- Views: 1098
Re: Units Check whack-a-mole
I'll take a look in greater depth Monday, but I tend to agree that these errors reflect some conceptual issues with the model. I find the rewilding equation extremely weird. I'd probably fix the units by adding an explicit parameter, with value 1, to make clear that there's an implicit conversion go...
- Sun Jul 30, 2023 12:57 am
- Forum: Vensim
- Topic: Reverse engineering
- Replies: 3
- Views: 491
Re: Reverse engineering
Generally a causal loop diagram can't be translated automatically to a model, because it simply doesn't contain enough information. The COIN diagram you posted actually has an underlying model that is much larger. https://metasd.com/2010/04/hypnotizing-chickens/ You should be able to turn a CLD into...
- Fri Jul 28, 2023 9:46 pm
- Forum: Vensim
- Topic: Units Check whack-a-mole
- Replies: 9
- Views: 1098
Re: Units Check whack-a-mole
A stock equation is the integral of a flow over time, so the stock unit has the flow unit * time unit. This is easier to see if you write the discrete update that happens with Euler integration: stock(t+dt) = stock(t) + dt*(inflows-outflows) were t=time, dt=TIME STEP in Vensim. This has units: stock...
- Fri Jul 28, 2023 9:19 pm
- Forum: Vensim
- Topic: Input Mode
- Replies: 2
- Views: 440
Re: Input Mode
I'm not sure what you mean by "input mode".
The conventional way to implement exponential growth is:
stock = INTEG( - outflow, initial stock ) ~ stuff
outflow = stock * loss rate ~ stuff/time
or
outflow = stock / lifetime
The conventional way to implement exponential growth is:
stock = INTEG( - outflow, initial stock ) ~ stuff
outflow = stock * loss rate ~ stuff/time
or
outflow = stock / lifetime
- Fri Jul 28, 2023 9:19 pm
- Forum: Vensim
- Topic: Input Mode
- Replies: 2
- Views: 440
Re: Input Mode
I'm not sure what you mean by "input mode".
The conventional way to implement exponential growth is:
stock = INTEG( - outflow, initial stock ) ~ stuff
outflow = stock * loss rate ~ stuff/time
or
outflow = stock / lifetime
The conventional way to implement exponential growth is:
stock = INTEG( - outflow, initial stock ) ~ stuff
outflow = stock * loss rate ~ stuff/time
or
outflow = stock / lifetime
- Fri Jul 28, 2023 2:38 am
- Forum: Vensim
- Topic: Units Check whack-a-mole
- Replies: 9
- Views: 1098
Re: Units Check whack-a-mole
The Log(Pop) error can be handled by defining something like unit pop == 1 ~ person and then normalizing logpop = log( pop/unit pop + 1 ) The other two errors seem like a unit problem with knowledge. Flows always have units of their associated stock, divided by the time unit. Therefore if learning a...
- Thu Jul 27, 2023 5:01 am
- Forum: Vensim
- Topic: Exogenous data in transportation model
- Replies: 8
- Views: 1346
Re: Exogenous data in transportation model
PLE doesn't include the stats tool unfortunately. You could generate a table and copy/paste to Excel or something for the comparison.
- Thu Jul 27, 2023 4:58 am
- Forum: Vensim
- Topic: The use of 'TIME STEP' in equations
- Replies: 8
- Views: 670
Re: The use of 'TIME STEP' in equations
However ... the TREND function does essentially what I proposed, without requiring the extra equation.
- Tue Jul 25, 2023 9:43 pm
- Forum: Vensim
- Topic: The use of 'TIME STEP' in equations
- Replies: 8
- Views: 670
Re: The use of 'TIME STEP' in equations
It sounds like you're trying to recover the value of a variable at a previous time step? This appears to be computing a growth rate or derivative? You could write something like: Previous Resident Income = SMOOTH(Resident Income,TIME STEP) income trend = ( (Resident Income - Previous Resident Income...
- Mon Jul 24, 2023 1:22 am
- Forum: Vensim
- Topic: Response Time
- Replies: 0
- Views: 5500
Response Time
Many of us are at #ISDC2023 so response times will be longer this week.