Search found 3999 matches
- Fri Jun 20, 2025 8:36 pm
- Forum: Vensim
- Topic: Non-integer Poisson Warning
- Replies: 2
- Views: 85
Re: Non-integer Poisson Warning
It still computes the payoff; fortunately that works because it uses the LogGamma function as a continuous generalization of factorial. Should be harmless, though perhaps we should suppress excessive warnings.
- Tue Jun 17, 2025 4:33 pm
- Forum: Vensim
- Topic: Resize first column of table?
- Replies: 3
- Views: 164
Re: Resize first column of table?
You're right ... as of at least 10.1.5 (Win) it was possible. So, regression ...
- Tue Jun 17, 2025 4:06 pm
- Forum: Vensim
- Topic: Resize first column of table?
- Replies: 3
- Views: 164
Re: Resize first column of table?
I'm not sure it was possible, but obviously it should be. In the old gui, it was possible to right-click (ctl-click) the table tool to change the default width. Also, the runname should be in its own column. Ticketing for improvement ...
- Sun Jun 15, 2025 10:14 pm
- Forum: Vensim
- Topic: What does fp_err_ctx do?
- Replies: 2
- Views: 367
Re: What does fp_err_ctx do?
These _should_ replicate an fp error. We'll take a look at the model. You might try turning on the payoff report, if it isn't already on, to reproduce.
- Mon Jun 09, 2025 3:17 am
- Forum: Vensim
- Topic: Can I vary the NOISE SEED in the .vsc text instead of the checkbox?
- Replies: 2
- Views: 1420
Re: Can I vary the NOISE SEED in the .vsc text instead of the checkbox?
Not if you're using the File method. But every time you run an mcmc, it now generates a vsc that runs the sample with that box checked.
For other methods (multivariate, latin hypercube) you can add NOISE SEED=VECTOR(...) to the list as an alternative.
For other methods (multivariate, latin hypercube) you can add NOISE SEED=VECTOR(...) to the list as an alternative.
- Fri Jun 06, 2025 2:42 am
- Forum: Vensim
- Topic: Does running Powell using DLL/Venpy generate '.out' file?
- Replies: 2
- Views: 2226
Re: Does running Powell using DLL/Venpy generate '.out' file?
The output should be the same. We'll have to take a look. Do you have a test case?
- Thu May 29, 2025 4:55 pm
- Forum: Vensim
- Topic: MCMC with multiple chains and starting points
- Replies: 3
- Views: 2595
Re: MCMC with multiple chains and starting points
One way to assess what's going on is to look at the _distrib file that gets generated. If you filter out the final sample and plot a parameter against iteration, you can see how the distribution evolves.
- Wed May 28, 2025 6:38 pm
- Forum: Vensim
- Topic: MCMC with multiple chains and starting points
- Replies: 3
- Views: 2595
Re: MCMC with multiple chains and starting points
No. There are three initialization methods: overdisperse, underdisperse, and hybrid (set by the MCINIT parameter). - over draws in the same way Powell multistart works, from a very broad powerlaw distribution (or uniform if both bounds are set); in the future, I'd like to modify this to draw from yo...
- Wed May 28, 2025 3:42 pm
- Forum: Vensim
- Topic: Modeling simultaneous substitution flows
- Replies: 3
- Views: 4408
Re: Modeling simultaneous substitution flows
I'm puzzled by your statement that "defining simultaneous flows in two directions unintentionally inflates total demand. For example, demand moves from Brand B to Brand A, and then flows back to Brand B." In your example, demand is conserved. If demand shifts from A to B, the demand for B ...
- Wed May 28, 2025 3:33 pm
- Forum: Vensim
- Topic: connectors to vars scrolled to not possible
- Replies: 3
- Views: 2318
Re: connectors to vars scrolled to not possible
Here's a possible workaround: Edit the equation for the destination variable. Add the source variable to the expression. When you exit, accept the request to add the source connection to the diagram. At this point, you'll have a straight arrow from source->destination. Navigate to the midpoint and c...
- Mon May 26, 2025 11:52 pm
- Forum: Vensim
- Topic: How to rea-add part of a flow?
- Replies: 2
- Views: 3736
Re: How to rea-add part of a flow?
I think it's possible - use the flow tool to click on the valve, then click on the target (whitespace for a cloud, or another stock). You may have an unwanted arrowhead at this point, which you can turn off with a right-click.
- Thu May 22, 2025 7:34 pm
- Forum: Vensim
- Topic: two constants as input, with a time delay on one constant
- Replies: 2
- Views: 2905
Re: two constants as input, with a time delay on one constant
Maybe this?
glucose in = infusion + endogenous
endogenous = STEP( endogenous rate, endogenous start time )
endogenous start time = 2
infusion = STEP( infusion rate, endogenous start time + infusion delay )
infusion delay = 4
glucose in = infusion + endogenous
endogenous = STEP( endogenous rate, endogenous start time )
endogenous start time = 2
infusion = STEP( infusion rate, endogenous start time + infusion delay )
infusion delay = 4
- Mon May 19, 2025 2:42 pm
- Forum: Vensim
- Topic: Help with Vensim
- Replies: 3
- Views: 3416
Re: Help with Vensim
There are also some video courses here https://vensim.com/video/
- Thu May 08, 2025 8:17 pm
- Forum: Vensim
- Topic: Tracking stock attributes
- Replies: 3
- Views: 4199
Re: Tracking stock attributes
Great. Another place this comes up a lot is in tracking bonds and mortgages. There's usually a mix of terms, which makes the simpler first-order version attractive for strategic models, as in your case.
- Wed May 07, 2025 4:09 pm
- Forum: Vensim
- Topic: How to model delayed flows due to unmet demand
- Replies: 2
- Views: 4116
Re: How to model delayed flows due to unmet demand
Something like this:
In queuing theory there's also the concept of "balking" where arrivals decline to joint the queue, because they immediately perceive that the line is too long.- Tue May 06, 2025 3:47 pm
- Forum: Vensim
- Topic: Tracking stock attributes
- Replies: 3
- Views: 4199
Re: Tracking stock attributes
I think the best option is to disaggregate the capacity stock into incentivized and older components. For example: capacity credit stock disagg.png There are two versions here. The top copy uses a standard first-order outflow on the stock of new incentive-eligible capacity. That may be appropriate f...
- Tue May 06, 2025 3:22 pm
- Forum: Vensim
- Topic: Tracking stock attributes
- Replies: 3
- Views: 4199
Tracking stock attributes
Reposting a question from metasd.com: How do I add a variable that tracks the “age of a stock”? I am looking at an energy system dynamics model where tax incentives are offered for the first 10 years of an installed capacity operation. I have stock representing the installed capacity but need to set...
- Mon May 05, 2025 3:43 pm
- Forum: Vensim
- Topic: "Sensitivity2All" for selected constants only
- Replies: 3
- Views: 6120
Re: "Sensitivity2All" for selected constants only
On the Advanced tab of the sens2all setup dialog, you can specify a savelist that excludes nuisance parameters:
- Mon May 05, 2025 3:39 pm
- Forum: Vensim
- Topic: Lookups in new equation editor
- Replies: 5
- Views: 5844
Re: Lookups in new equation editor
Note that the [+] button becomes visible after you make the initial family selection:
- Mon May 05, 2025 3:35 pm
- Forum: Vensim
- Topic: Lookups in new equation editor
- Replies: 5
- Views: 5844
Re: Lookups in new equation editor
It's a two-tier process. First (and only once), set the family associated with the equation: sub families.png Then, if you need distinct equations for subranges or specific elements, right-click the tab or use the dropdown on the Subscripts button to set those: sub elements.png sub element 2.png
- Sat May 03, 2025 1:44 pm
- Forum: Vensim
- Topic: Lookups in new equation editor
- Replies: 5
- Views: 5844
Re: Lookups in new equation editor
It works - example: subscript 2025-05-03_07-37-19.png Procedure: Click the Subscripts button the first time you add ranges to set the relevant families Use the [+] button to add a tab if you need an additional element Right-click the new tab to set Subranges and Elements (and Exceptions if any) ... ...
- Mon Apr 28, 2025 1:05 pm
- Forum: Vensim
- Topic: Vensim: How to I add value annually
- Replies: 4
- Views: 4655
Re: Vensim: How to I add value annually
Putting PULSE TRAIN in the Initial Value field, as in your second example, won't work because the initial value doesn't change - it just initializes the stock. In your first example, if "Input" is constant at 1.1M and "Recycled Plastic & Monomer Feedstock" is constant, that m...
- Wed Apr 02, 2025 6:21 pm
- Forum: Vensim
- Topic: insert picture into Aux / Stock variable?
- Replies: 8
- Views: 9161
Re: insert picture into Aux / Stock variable?
Funny. I think there's probably a font that would make those unicode chars cross-platform, but it wasn't obvious which one. The model runs though.
- Wed Apr 02, 2025 3:55 pm
- Forum: Vensim
- Topic: Watermark model output?
- Replies: 3
- Views: 2772
Re: Watermark model output?
I think you can specify page header/footer info if you print to PDF?
- Wed Apr 02, 2025 2:55 pm
- Forum: Vensim
- Topic: identifying contributors to large file size and slow run time
- Replies: 16
- Views: 14865
Re: identifying contributors to large file size and slow run time
For file size, the most likely candidate is heavily-subscripted variables. We don't have a way to identify these built in, but here's a trick: - export a run to a tab or csv file, with subscripts in their own columns - to minimize the file size, you can set the time range to capture just the first 2...