Search found 3806 matches

by tomfid
Mon Oct 30, 2023 9:12 pm
Forum: Vensim
Topic: Vensim 10.1.1 macOS GUI Bug
Replies: 8
Views: 4085

Re: Vensim 10.1.1 macOS GUI Bug

I think this is an instance of one we're working on ... seems to be random breakage of the GUI library. Are you using Sonoma or Ventura or another OS version?
by tomfid
Mon Oct 30, 2023 9:09 pm
Forum: Vensim
Topic: Random number generator; any tips to replicate?
Replies: 15
Views: 10519

Re: Random number generator; any tips to replicate?

LAUJJL wrote: Mon Oct 30, 2023 5:09 pm
Another problem is with games.
If you stop a game at a certain time, the random generator may be reinitialized. And the behavior of some random variables may change.
I think this would be a bug; if you have an example, we'd be interested.
by tomfid
Mon Oct 30, 2023 9:07 pm
Forum: Vensim
Topic: Random number generator; any tips to replicate?
Replies: 15
Views: 10519

Re: Random number generator; any tips to replicate?

Restating what I stated above for clarity: If a modeler wanted every RANDOM-based function in a model to be independent of all of the others (not drawing from the same pool), then the functions should be called with different STREAM_IDS (https://www.vensim.com/documentation/stream_id.html). Someone...
by tomfid
Mon Oct 30, 2023 9:03 pm
Forum: Vensim
Topic: Random number generator; any tips to replicate?
Replies: 15
Views: 10519

Re: Random number generator; any tips to replicate?

For instance, a model has RANDOM_UNIFORM and RANDOM_NORMAL, and is run to generate output1.vdfx. If a user then deletes the UNIFORM() function in one portion of the model and adds a UNIFORM() function in a different part of the model, will the functions be called in the same order? Will the random ...
by tomfid
Mon Oct 30, 2023 8:56 pm
Forum: Vensim
Topic: Vensim DSS Crashing on Save When Viewing As Sketch
Replies: 5
Views: 953

Re: Vensim DSS Crashing on Save When Viewing As Sketch

This has a lot of undefined variables that appear as A FUNCTION OF() in the text listing. Was the last operation before the crash a huge paste/replicate or something? There's some other strange stuff, like the string STX{...} in one equation. Do you have a previous edition of the model for compariso...
by tomfid
Fri Oct 27, 2023 7:57 pm
Forum: Vensim
Topic: BUG? Control-<number> not select analysis tool
Replies: 4
Views: 2116

Re: BUG? Control-<number> not select analysis tool

Sounds like a bug, because it's still working on Win10 (assuming you're using a Mac).
by tomfid
Fri Oct 27, 2023 1:10 pm
Forum: Vensim
Topic: When will the tool replacing Venapp available?
Replies: 11
Views: 1357

Re: When will the tool replacing Venapp available?

Are you looking for screen layout tools, or scripting/automating a set of actions to support interactive gaming or similar?
by tomfid
Thu Oct 26, 2023 2:34 pm
Forum: Vensim
Topic: Cannot access Run configuration manager
Replies: 3
Views: 673

Re: Cannot access Run configuration manager

You might be using the old GUI. Tools>Switch to New GUI

Does that do it?
by tomfid
Thu Oct 26, 2023 2:23 pm
Forum: Vensim
Topic: Random number generator; any tips to replicate?
Replies: 15
Views: 10519

Re: Random number generator; any tips to replicate?

The version we're using is a little older, but same thing. It was very easy to implement - nothing special needed, but we did do extensive verification using the NIST suite and DieHard to be sure it was working. I think the goal of replication with random functions may be elusive, because order and ...
by tomfid
Thu Oct 26, 2023 1:04 pm
Forum: Ventity
Topic: Function: choose
Replies: 4
Views: 4730

Re: Function: choose

Generically, I'd say the HH decides to migrate, then runs a Process List action to evaluate possible target regions. These are sorted by GSP or some more general measure of attractiveness. You limit processing to one iteration, and the HH changes its location attribute to match the leading candidate...
by tomfid
Wed Oct 25, 2023 7:41 pm
Forum: Vensim
Topic: When will the tool replacing Venapp available?
Replies: 11
Views: 1357

Re: When will the tool replacing Venapp available?

Two other things are also available now:
- SDEverywhere https://sdeverywhere.org/
- Vensim publishing to WebAssembly https://www.vensim.com/documentation/pu ... -inte.html
by tomfid
Tue Oct 24, 2023 5:42 pm
Forum: Vensim
Topic: What can be done to speed up model calibrations and MCMC?
Replies: 4
Views: 623

Re: What can be done to speed up model calibrations and MCMC?

Memory is generally not a constraint, and GPU acceleration is not supported. In the multicore version, speed is basically just cores x clock speed. If you have BIOS access to the machine, there may be some advantage to turning off hyperthreading, but this is a relatively small factor.
by tomfid
Tue Oct 24, 2023 5:39 pm
Forum: Vensim
Topic: Error Message
Replies: 6
Views: 868

Re: Error Message

The subscript on QPD0 on the left side is vcd, and on the right side it's vc'd or vcd'. I'm not sure if the ' (prime) refers to differentiation or something else, but it's possible that the left and right side expressions are distinct things.
by tomfid
Tue Oct 24, 2023 5:35 pm
Forum: Vensim
Topic: What can be done to speed up model calibrations and MCMC?
Replies: 4
Views: 623

Re: What can be done to speed up model calibrations and MCMC?

Are you running the latest multicore v10 version?

With Powell you need to select the XPARALLEL multistart option.

With MCMC you don't need to change anything. Initialization is not multithreaded, so you may want to switch to the "Underdisperse" method to get things going faster.
by tomfid
Tue Oct 17, 2023 2:36 pm
Forum: Vensim
Topic: Find a shadow variable
Replies: 2
Views: 494

Re: Find a shadow variable

In v10+, select the variable on the diagram, making it the workbench var.

Hit F4, or menu Edit>Find Workbench. This will find the next instance of that variable.

If that's not the source node, hit F3, or menu Edit>Find Again.
by tomfid
Mon Oct 16, 2023 3:41 pm
Forum: Vensim
Topic: Multivariable data lookup and interpolation
Replies: 1
Views: 748

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...
by tomfid
Sun Oct 08, 2023 8:07 pm
Forum: Vensim
Topic: If then else function
Replies: 1
Views: 453

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...
by tomfid
Fri Oct 06, 2023 2:50 pm
Forum: Vensim
Topic: Subscript for time based variabel
Replies: 4
Views: 404

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...
by tomfid
Fri Oct 06, 2023 2:12 pm
Forum: Vensim
Topic: Subscript for time based variabel
Replies: 4
Views: 404

Re: Subscript for time based variabel

There's a subscripted project model in the User Guide:
https://www.vensim.com/documentation/21195.html
by tomfid
Tue Oct 03, 2023 8:42 pm
Forum: Vensim
Topic: Error opening older SD models in published works (Macintosh vmf files)
Replies: 2
Views: 784

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...
by tomfid
Tue Oct 03, 2023 4:38 pm
Forum: Vensim
Topic: best way to build a server for clients via the internet
Replies: 14
Views: 947

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.
by tomfid
Tue Sep 26, 2023 7:31 pm
Forum: Vensim
Topic: Reference modes in Vensim PLE
Replies: 3
Views: 435

Re: Reference modes in Vensim PLE

I can replicate this - it's a bug.
by tomfid
Thu Sep 21, 2023 4:44 pm
Forum: Vensim
Topic: How to set up DSS to compile to C
Replies: 1
Views: 254

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...
by tomfid
Fri Sep 15, 2023 3:52 pm
Forum: Vensim
Topic: Random with Log Normal distribution
Replies: 2
Views: 309

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...
by tomfid
Wed Sep 13, 2023 7:17 pm
Forum: Vensim
Topic: Checking for NA input data with subscripts
Replies: 4
Views: 445

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...