Ventana software support forum

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.

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.

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...

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...

On the Advanced tab of the sens2all setup dialog, you can specify a savelist that excludes nuisance parameters:

Note that the [+] button becomes visible after you make the initial family selection:

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

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) ... ...

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...

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.

I think you can specify page header/footer info if you print to PDF?

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...

Right - the key (in the screenshot above) is that the Equation type is set to Initial, which which really just wraps the right side of the equation in INITIAL, i.e. var = INITIAL( GET DATA MIN( blabla ) ) INITIAL is restricted, such that it has to be the first thing on the right side of the equation...

Ultimately, the model was still very slow. And I worked out why, and I had this same problem about 10 years ago. It's not obvious, so I'll post: I had a stock with a large number elements in several subscript variables, e.g. 106 age elements, 3800 geographies, gender, etc. As I was building the mod...

Administrator wrote: ↑Mon Mar 10, 2025 3:52 pm No benefit in using a CIN rather than data. Do whatever is easiest.

I'm not convinced that's true. A data equation has a little overhead at every time step. A constant does not. I only use data for things that actually have time variation.

I assume the outflow is just aging[age18] ? I think we need more of the equations, or preferably a small model example.

Is the TIME STEP essentially discrete (i.e. same as the age increment in the subscript)?

Accumulation implies a stock, so you could create a stock of Cumulative GDP with an inflow of Current GDP. Note that this implies a change of units (if the flow is $/year, and the stock is $ for example).

Re #2, when you say "predefined equation", are you referring to the function list? We removed that in favor of predictive typing. However, the list is still there:

If the graphical lookup editor is missing, use the "switch" button: You can delete on the graph with the red - button: You can show/hide the table of values:

Nice!

You could potentially link it in via VenPy, though that wouldn't be totally standalone. https://github.com/VensimSoftware/venpy

Another option would be to translate models to PySD. https://github.com/SDXorg/pysd

Another good test would be to switch to new 10.3. When you install, you could try checking the boxes to reset settings to default.

You can also build a simple interface on the diagram, without any additional tools.

You might try opening them in Inkscape (open source SVG-based vector image editor) to see if there's a clipping rectangle or something that is interfering.

This is already possible in the legacy equation editor - use the Jump to Hilite button.

In the new editor, it's a right-click->edit equation.