Ventana software support forum

Have you scaled your input vectors to order of magnitude 1? There may be numerical precision issues if not.

If the output is constant, then it seems that your inputs must be constant as well (unless the table function relationships are flat). So, the question is, which of your inputs should be varying, and why? You can implement variation in the inputs with test inputs like STEP, PULSE, or SIN, or a looku...

Also see
http://dspace.mit.edu/handle/1721.1/11105

Is the oscillation you want a test input in schedule pressure, or desired behavior of quality?

Presumably you estimated something like quality = a + b*schedule pressure + err. You can implement that directly in an equation, by importing the a,b coefficients from your estimation. However, it's not likely to be robust, in that quality might take on impossible values for some values of schedule ...

TIME STEP determines how finely time is sliced when the model is integrated. You might get some insight from this ... http://www.vensim.com/documentation/eul ... ime%2Bstep

One further thought: unit checking and syntax checking don't really interact, so the correction of the 40 errors from splitting the dimensioned and dimensionless items must be related to the subscripting implications of doing that rather than the units themselves. Any further insight into the detail...

Understood.

External functions don't pass units through, but you can normalize all the inputs to dimensionless quantities (perhaps by dividing with a dummy variable, like furlongs per fortnight == 1 ~ furlong/fortnight ).

You'll have to visit each view, but it's fairly quick to do the following:
- hit the 'h' key as needed, so you can see everything
- <control>A to select all
- Edit>Hide to Depth>Unhide

I've put this on the list of things to look at for 6.4.

Ahh ... that's a different matter. It should indeed work. I assume you have your Tools>Options>Startup>External Function Library path pointed at the right .dll. The /comp folder should include a precompiled venext.dll - you might try pointing at that to see what happens. Have you installed any later...

Did you remember to add the functions to the definition list in section 3 of venext.c? /**************************************************** 3 - Grouping of functions in a structure - see venext.h ***********************************************************/ static FUNC_DESC Flist[] = { {"COSINE...

Yikes! Can you post the model, or email it to us so we can take a look?

I think your diagnosis may be correct - the error message is incorrect. If I paste your code into the text editor in an empty model, I get the same "on the right not the left" error. The actual problem, though, is that SBHB4 and STHBX1 are undefined. If I add them as data variables, the er...

OK - I can replicate the message.

Incidentally, as a shortcut, you can rewrite subscripts like this hierarchically, like:

Can you supply an example of one of the equations that generates such a message? In a normal model (no external functions), subscripting errors will generally be proximate to the warning messages - i.e., the message either takes you to the erroneous equation, or one of the inputs on the right side i...

If you could do the automation with a sensitivity control file, there's a "Display warning messages" option that would write all the runtime errors to the screen log. Some optimization options write a log file containing errors, but not always - I'll have to look at the code to see what th...

Hi JJ - The time series output for variables in the .lst is stored in the .vdf for the simulation run. You can get at it with the sensitivity graph, bar graph histogram, or stats tool options. For other analysis, you can extract the raw output by exporting the dataset (Model>Export Dataset...). - Tom

There are two options: Build a structure in the model that generates the correlation (there's a bivariate normal example in http://www.vensim.com/documentation/Models/OptSensi /MCMC). Generate a sample using some other tool and use the File sensitivity option. http://www.vensim.com/documentation/sen...

There are many options in DSS. You can use the "Import Vals" button in a lookup, though generally data variables are preferred unless you need specific lookup functionality. You can use GET XLS DATA or similar: http://www.vensim.com/documentation/fn_get_xls_data.htm or import from a file -...

PLE isn't really designed for much data work - for that you need a more advanced version. If you want to import the data to a vdf (e.g., for comparison with model output) you need to use the .dat format: http://www.vensim.com/documentation/23460.htm Your Excel workbook is close to that - you'd just ...

That helps. I'll see if I can create something.

What you really need to simplify the accounting is the SAMPLE IF TRUE function in Vensim Pro or DSS.

I'm finding it quite messy to create a structure that meets this spec, using only the functions in PLE. I can't think of real physical process that has precisely this behavior. What are we actually modeling here?

Are you looking for pulses of controllable width and height, at random times? That can be implemented with a stock structure - I could cook up a demo structure if that's what you're after.

Vensim DSS is commercial software and requires a license. We're fans of open source ourselves, but the reality is that DSS is a very complex piece of software that wouldn't thrive as open source. Without a revenue stream to support it, there wouldn't be a Vensim, and we couldn't support free PLE eit...

Note that in DSS/Pro you wouldn't have to do this manually, because you can automatically add causes to the diagram, and even add variables to the model, from within the equation editor.