Ventana software support forum

If the time step for your model is in days, the following should work. Use the "ORDER NOW FLAG" to trigger the order. Tony. TIME BETWEEN ORDERS = 30 Units : Day ORDER NOW FLAG = IF THEN ELSE ( Time Since Last Order >= TIME BETWEEN ORDERS , 1 , 0 ) Units : DMNL RESET TIME SINCE LAST ORDER =...

>> I suspect that the vendlstc.dll file that I am using is from an 5.10d or
>> possibly earlier. Would that cause the problem?
Yes. The version number that the DLL asks for needs to be the same as the one supplied by the external function library (if that makes sense).

Tony.

You cannot do this at present.

I'll add it to the wish list of things to be able to do though.

Tony.

Recent versions of the external function library do not need linking with vensim.lib any more. What exactly is the error you are getting when trying to run a model with external functions? And are you applying a vensim.ini file (that loads the external functions) when loading the multi-context DLL? ...

In the source code, there will be an include line something similar to #include "c:\\program files\\......\\vensim.h" This needs to point to the new vensim.h file installed by 5.10e. In Windows 7, the file is located at something like C:\Documents and settings\User Profiles\Public\Vensim\c...

I don't think it is possible, but I will have a look at the settings to see if I can do something.

Tony.

This operates in exactly the same way as Vensim does (once the sim is over, everything resets). What you need to do is write the values before the sim starts and then load them back in once it's over. Something like the following commands on a button. SIMULATE>WRITECIN|temp.cin <Run the model here> ...

Are you using Vensim? If yes, there is a good introduction to delays at http://www.vensim.com/documentation/index.html?mgu09_continuous_versus_discrete_delays.htm It includes a link to a model that uses lots of different delay types. Also take a look at the molecules which also have some delay struc...

You cannot change lookup tables during a game/simulation.

You cannot convert lookup variables to game variables.

What are you trying to do and maybe we can help a little better?

You can not do the conversion in Java.

Edit the model in Vensim, and say for example you have a constant called "COST PER WIDGET". Make the equation for this COST PER WIDGET = GAME ( <start constant> ).

Now you will be able to change it during a simulation.

SETVAL will only set constants, so will only work before a simulation starts.

If you want to change the values as the simulation progresses, you need to run it as a game. Have a look at chapter 11 in the user guide, this talks about games.

Tony.

You probably will not get many (if any) answers on this forum regarding Stella, as we are all Vensim users (some of us have experience using Stella, but not many). It might be better to ask at the SD Society forum (http://www.systemdynamics.org/forum) or search through the archives of the SD mailing...

There is a section in the help system about Stella to Vensim conversion. Do a search for Stella. http://www.vensim.com/documentation/index.html?24290.htm I cannot help regarding the free models for K12 science. You could try specifying in a little more detail what you need (I have no idea what K-12 ...

The only way to do this would be to direct the user to the model reader download, or build a custom installation yourself. Either way, they will need to run an installation of some type. Maybe Forio could do what you need? They can host Vensim simulations, so you could just direct the user to the co...

You can do this only with a redistribution kit. But you can give them a copy of the model reader at the same time as your model (and there would be nothing stopping you from developing a custom installation with the model reader embedded). Most things need a reader of some sort installed to view thi...

I think when you are running the model, it is saving the run to the model directory. Have you called "SIMULATE>RUNNAME|" and passed in the correct file name (eg, the following instructs the Vensim engine to save the file "run1.vdf" to the "uncertainty" sub-directory) Ca...

Where is the data coming from? If it's Excel, do the calculation in Excel and read it back to Vensim.

try

running max of some var =
SAMPLE IF TRUE ( some var > running max of some var , some var , some var )

This looks like a bug to me.

I've tried it all the ways I can think of and it does not seem to give the slope value.

Hi, I have a DATA variable XX that is read from an Access database. The table for XX requires 12 subscripts to determine a value, that is value = XX[ sub1, sub2, ...sub12]. The subscripts contain a combination of numeric and literal values. Since Vensim subscripting allows only a max of 8 subscript...

Why is everything in the model subscripted with the "P1" element? This is the problem in the model.

Tony.

PS. You really should put dimensions in this model.

How about something like FLIGHT ID[FLIGHT] = INITIAL(FLIGHT) FIRST FLIGHT ID AVAILABLE = VMIN ( if then else ( flight slot free[FLIGHT!] = 0 , FLIGHT ID[FLIGHT!] , 9999999 ) ) If there are no flight slots available it will return 9999999, if there is one, it will return the ID number of the subscript.

You haven't really given us anything to advise on. There is little we can do if we just have an equation to work with. Try getting a simple example working first so you understand it, then move towards the example you gave. There is some additional information on it at http://www.vensim.com/allocp.h...

This kind of discussion can go on and on, and I'm sure you can find some info in the SD mailing list archives (http://www.ventanasystems.co.uk/forum/viewforum.php?f=34). But if it helps, I think of SD as trying to understand the "whole system". Mathematics comes into it, but the goal reall...