Search found 3049 matches

by tomfid
Tue Aug 25, 2020 4:11 pm
Forum: Vensim
Topic: Sort Order (for multivariable)
Replies: 21
Views: 485

Re: Sort Order (for multivariable)

The documentation for the allocation process is here: https://www.vensim.com/documentation/allocation_overview.htm The basic idea is that the unit costs are used to construct an aggregate supply curve. Then it computes the market-clearing costs, where demand intersects that curve. Any plant below th...
by tomfid
Tue Aug 25, 2020 3:57 pm
Forum: Vensim
Topic: Calibration vensim model
Replies: 9
Views: 328

Re: Calibration vensim model

https://www.vensim.com/documentation/usr18.htm It's generally best to do some hand calibration first, before you start automatically calibrating. I typically build myself a control panel, with graphs that compare model to data, or show other key outputs, and candidate parameters to include in the o...
by tomfid
Tue Aug 25, 2020 3:54 pm
Forum: Vensim
Topic: Getting the y-axis value
Replies: 13
Views: 303

Re: Getting the y-axis value

You can use SAMPLE IF TRUE or a stock to store the value of a variable at a particular time.

You can't access values in the future.
by tomfid
Fri Aug 21, 2020 4:10 pm
Forum: Vensim
Topic: Calibration vensim model
Replies: 9
Views: 328

Re: Calibration vensim model

This is a very big topic - you might start by posing the particular problem you're working on, describing the data available and what you'd like to get out of the model.
by tomfid
Fri Aug 21, 2020 1:31 pm
Forum: Vensim
Topic: Vensim hangs when switching to Text view
Replies: 8
Views: 220

Re: Vensim hangs when switching to Text view

I found the ALLOC problem only in the 32 bit version, so this is strange.
by tomfid
Thu Aug 20, 2020 11:03 pm
Forum: Vensim
Topic: Crashes frequently on Windows 10
Replies: 19
Views: 1789

Re: Crashes frequently on Windows 10

The problem is that both
CONTAMINACIÓN
and
Contaminación
exist in the model. I'm not sure how this could happen, except perhaps in an old pre-unicode version of Vensim.

The attached deletes the offending duplicates.
Mapeo rápido 2.mdl
(66.52 KiB) Downloaded 8 times
by tomfid
Thu Aug 20, 2020 4:03 pm
Forum: Vensim
Topic: Crashes frequently on Windows 10
Replies: 19
Views: 1789

Re: Crashes frequently on Windows 10

Deleting one instance doesn't solve the problem for me. I think there may be multiple problems, or something deeper.
by tomfid
Thu Aug 20, 2020 2:40 pm
Forum: Vensim
Topic: Crashes frequently on Windows 10
Replies: 19
Views: 1789

Re: Crashes frequently on Windows 10

I can replicate the problem. We should have a solution soon.
by tomfid
Wed Aug 19, 2020 11:37 pm
Forum: Vensim
Topic: Formula for modelling seasonality
Replies: 5
Views: 173

Re: Formula for modelling seasonality

Great. Feel free to keep asking questions ...
by tomfid
Wed Aug 19, 2020 1:36 pm
Forum: Vensim
Topic: Vensim hangs when switching to Text view
Replies: 8
Views: 220

Re: Vensim hangs when switching to Text view

Can you post or email the model? What Vensim version are you using?
by tomfid
Tue Aug 18, 2020 10:32 pm
Forum: Vensim
Topic: Problem with MCMC posterior sampling
Replies: 11
Views: 370

Re: Problem with MCMC posterior sampling

Ah ... the log transform makes sense. I suspect the fix to the prior payoff will make a significant difference.
by tomfid
Tue Aug 18, 2020 5:55 pm
Forum: Vensim
Topic: Sort Order (for multivariable)
Replies: 21
Views: 485

Re: Sort Order (for multivariable)

Great! You're most welcome.
by tomfid
Tue Aug 18, 2020 5:54 pm
Forum: Vensim
Topic: Problem with MCMC posterior sampling
Replies: 11
Views: 370

Re: Problem with MCMC posterior sampling

OK, I see two issues, both easy to fix: The payoff is intended to be a log likelihood, and the individual prior terms are log likelihoods, so the Prior Payoff equation should be a sum, not a product. The range on overwintering density in the voc is set to 16-18 (roughly), but the actual parameter va...
by tomfid
Tue Aug 18, 2020 4:12 pm
Forum: Vensim
Topic: Sort Order (for multivariable)
Replies: 21
Views: 485

Re: Sort Order (for multivariable)

There are at least two ways to create a subrange: 1. If you already have unit : (u1-u9) you can create subunit : (u3-u6) and it will automatically appear in the subrange list. 2. You can build them up hierarchically, by first defining unit low : (u1-u4) unit high : (u5-u9) then merging those with: u...
by tomfid
Tue Aug 18, 2020 4:09 pm
Forum: Vensim
Topic: Sort Order (for multivariable)
Replies: 21
Views: 485

Re: Sort Order (for multivariable)

coal,gas,hydro,re -> (unit:c unit,g unit,h unit) won't work, because you can't map 4 elements to 3 elements. Perhaps "re unit" doesn't exist as a member of "unit"?
by tomfid
Tue Aug 18, 2020 4:07 pm
Forum: Vensim
Topic: Sort Order (for multivariable)
Replies: 21
Views: 485

Re: Sort Order (for multivariable)

I used subscript mapping: https://www.vensim.com/documentation/re ... apping.htm and subranges: https://www.vensim.com/documentation/22100.htm

You may find it helpful to switch to text view to see the raw subscript equations.
by tomfid
Tue Aug 18, 2020 1:55 pm
Forum: Vensim
Topic: Problem with MCMC posterior sampling
Replies: 11
Views: 370

Re: Problem with MCMC posterior sampling

Just getting to this now, and it appears that the .voc and .vpd are not in the archive. Would you mind posting those?
by tomfid
Mon Aug 17, 2020 6:00 pm
Forum: Vensim
Topic: Problem with installation of VENSIM PLE
Replies: 6
Views: 210

Re: Problem with installation of VENSIM PLE

Hmm ... what operating system?
by tomfid
Mon Aug 17, 2020 2:14 pm
Forum: Vensim
Topic: Problem with installation of VENSIM PLE
Replies: 6
Views: 210

Re: Problem with installation of VENSIM PLE

Did you rename the installer .exe file when you downloaded it? Taking the error message literally, that might be the problem.
by tomfid
Sun Aug 16, 2020 3:15 pm
Forum: Vensim
Topic: Formula for modelling seasonality
Replies: 5
Views: 173

Re: Formula for modelling seasonality

Two things:
- your time bounds are inconsistent (months from 2000-2100, which implies years)
- there are quite a few unit errors, some of which may be conceptual problems - the floating point error in "net increase" is probably a conceptual issue revealed by units
by tomfid
Sun Aug 16, 2020 4:06 am
Forum: Vensim
Topic: Problem with MCMC posterior sampling
Replies: 11
Views: 370

Re: Problem with MCMC posterior sampling

Got it.
by tomfid
Sat Aug 15, 2020 9:17 pm
Forum: Vensim
Topic: Problem with MCMC posterior sampling
Replies: 11
Views: 370

Re: Problem with MCMC posterior sampling

One possible trick I'm thinking about is to log-transform one or two of the parameters that have large scale variations. That might make things behave better.
by tomfid
Sat Aug 15, 2020 9:16 pm
Forum: Vensim
Topic: Problem with MCMC posterior sampling
Replies: 11
Views: 370

Re: Problem with MCMC posterior sampling

This all looks pretty good, except for the corner problem. You can send a copy to vensim at vensim.com.
by tomfid
Sat Aug 15, 2020 7:22 pm
Forum: Vensim
Topic: Problem with MCMC posterior sampling
Replies: 11
Views: 370

Re: Problem with MCMC posterior sampling

How many parameters are hitting the boundary? Just this one, or several of the 7? (If several, it might be getting stuck in a corner.) I'm a little surprised that wider ranges, or no ranges, have convergence problems. The dimensionality isn't that great here. Is the model shareable for testing? A hy...
by tomfid
Fri Aug 14, 2020 1:55 pm
Forum: Vensim
Topic: Formula for modelling seasonality
Replies: 5
Views: 173

Re: Formula for modelling seasonality

You're on the right track. One option for a controllable wave is: COS( (time-phase)/period*2*pi ) where phase is the timing of the peak as a time relative to 0, not as an angle and pi=3.1415926. A more general strategy is: - use MODULO(time,period) to create a repeating index - for example, period m...