Search found 3816 matches
- Mon Oct 16, 2023 3:41 pm
- Forum: Vensim
- Topic: Multivariable data lookup and interpolation
- Replies: 1
- Views: 1007
Re: Multivariable data lookup and interpolation
You have a syntax problem - '1' is not a valid cell reference. https://www.vensim.com/documentation/fn_get_xls_constants.html Not sure what you have in mind for interpolation. You have 4 inputs, but since they have to sum to 100%, it looks like a 3D space. I'm not sure there's a general procedure fo...
- Sun Oct 08, 2023 8:07 pm
- Forum: Vensim
- Topic: If then else function
- Replies: 1
- Views: 530
Re: If then else function
Ugh. The general framework will be something like: QFP1 = IF THEN ELSE( tfp>0 , IF THEN ELSE( expression beginning with pp>0 ,expression beginning with sum over QH ,expression beginning with sum over QH*fraction with pp in numerator ) , 0 ) It's pretty confusing subscripting though - I would strongl...
- Fri Oct 06, 2023 2:50 pm
- Forum: Vensim
- Topic: Subscript for time based variabel
- Replies: 4
- Views: 492
Re: Subscript for time based variabel
It's not really a comprehensive project model, but it does show how to set up the subscripting. Unless you do some really arcane stuff, you won't really be doing CPM in Vensim (or any other SD tool). But that's kind of the point: CPM ignores the cross-stage rework cycle, partial concurrency, and oth...
- Fri Oct 06, 2023 2:12 pm
- Forum: Vensim
- Topic: Subscript for time based variabel
- Replies: 4
- Views: 492
Re: Subscript for time based variabel
There's a subscripted project model in the User Guide:
https://www.vensim.com/documentation/21195.html
https://www.vensim.com/documentation/21195.html
- Tue Oct 03, 2023 8:42 pm
- Forum: Vensim
- Topic: Error opening older SD models in published works (Macintosh vmf files)
- Replies: 2
- Views: 1244
Re: Error opening older SD models in published works (Macintosh vmf files)
This must predate Apple reversing its approach to big/little endian byte order. I was able to open it in 6.4, but it runs with an error. In the meantime, my similar replication is here: https://metasd.com/2010/03/behavioral-analysis-of-learning-curve-strategy/ This copy is from an earlier version of...
- Tue Oct 03, 2023 4:38 pm
- Forum: Vensim
- Topic: best way to build a server for clients via the internet
- Replies: 14
- Views: 1152
Re: best way to build a server for clients via the internet
The fee part is a good argument for Forio. They have the architecture for paid use of models; creating that yourself is probably a substantial bit of work.
- Tue Sep 26, 2023 7:31 pm
- Forum: Vensim
- Topic: Reference modes in Vensim PLE
- Replies: 3
- Views: 526
Re: Reference modes in Vensim PLE
I can replicate this - it's a bug.
- Thu Sep 21, 2023 4:44 pm
- Forum: Vensim
- Topic: How to set up DSS to compile to C
- Replies: 1
- Views: 350
Re: How to set up DSS to compile to C
The section you want is in the docs, https://www.vensim.com/documentation/25945.html, but I see it's out of date. Generally what you need (assuming Windows) is: Edit C:\Users\Public\Vensim\vengine\comp\MDLDP64.BAT (this is the compilation script) Early on, you'll see a series of blocks that set up t...
- Fri Sep 15, 2023 3:52 pm
- Forum: Vensim
- Topic: Random with Log Normal distribution
- Replies: 2
- Views: 405
Re: Random with Log Normal distribution
Yes! I usually do something like the following: var = GeometricMean * EXP( GeometricSD*RANDOM NORMAL(-6,6,0,1,0) ) The GeometricMean has the same units as your target variable. The GeometricSD is the standard deviation as a fraction of the mean, i.e. the standard deviation of LN(var/GeometricMean) a...
- Wed Sep 13, 2023 7:17 pm
- Forum: Vensim
- Topic: Checking for NA input data with subscripts
- Replies: 4
- Views: 538
Re: Checking for NA input data with subscripts
I think your instincts were good here. Leaving the data in .vdf format should normally work. It's possible that there was a leak in 6.3 that allowed the NAN values to get into the vdf in the first place. For doing a round-trip vdf/vdfx conversion, .dat format is often the easiest, because it doesn't...
- Tue Sep 12, 2023 7:54 pm
- Forum: Vensim
- Topic: Checking for NA input data with subscripts
- Replies: 4
- Views: 538
Re: Checking for NA input data with subscripts
If you want to check for :NA: in a data variable, you need to use the :RAW: interpolation method. :INTERPOLATE: only returns :NA: if the series has no data at all.
- Mon Sep 04, 2023 2:50 pm
- Forum: Vensim
- Topic: Sensitivity analysis using the file option in a subscripted model
- Replies: 13
- Views: 882
- Mon Sep 04, 2023 2:49 pm
- Forum: Vensim
- Topic: Sensitivity analysis using the file option in a subscripted model
- Replies: 13
- Views: 882
Re: Sensitivity analysis using the file option in a subscripted model
When I save this as tab-delimited text, Excel quotes the column headers like "fracDWI[Male,Age15]" This is a nonstandard behavior, because quotes are not needed when the delimiter is tab (only csv). Unfortunately this is not legitimate quoting in Vensim (the subscript brackets should not b...
- Fri Aug 25, 2023 2:50 pm
- Forum: Vensim
- Topic: unit consistency bug
- Replies: 5
- Views: 1987
Re: unit consistency bug
Thanks Tom I also did not notice the mile per trip is constant, but still interesting how can this happen if there is a link between two variables. It should automatically make constant become AUX. I'm not sure we should do this, because the extra arrow could be a mistake. In the language, constant...
- Fri Aug 25, 2023 2:47 pm
- Forum: Vensim
- Topic: Error in a counter variable
- Replies: 6
- Views: 667
Re: Error in a counter variable
Here are some options.
I think one unit error might have been a typo in "dmnl".
I think one unit error might have been a typo in "dmnl".
- Fri Aug 25, 2023 2:25 pm
- Forum: Vensim
- Topic: Download link not working on any browser
- Replies: 7
- Views: 580
Re: Download link not working on any browser
Antivirus?
- Fri Aug 25, 2023 2:24 pm
- Forum: Vensim
- Topic: Sensitivity analysis using the file option in a subscripted model
- Replies: 13
- Views: 882
Re: Sensitivity analysis using the file option in a subscripted model
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].
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].
- Thu Aug 17, 2023 5:46 pm
- Forum: Ventity
- Topic: Entity activation time
- Replies: 5
- Views: 3368
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: 1987
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: 1987
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: 3451
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: 3451
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: 3368
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: 3368
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: 622
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...