Ventana software support forum

the variation of a variable from one step to the other will be slowed or accelerated with the decrease or increase of the time step indeed. If you are running at 20 kilometers an hour, the length of the journey in a millisecond will be shorter than in an hour. But it will not change the overall spee...

One remark to Pruyn explanation. It is possible to transform an array of two or more subscritps into a vector and when the work is done to retransform back the results in your vector into the array. I have done it with the vector sort order function that works only with one subscript, it works fine....

<my question here is that there are two compnies in the market and each company has three technologies to produce the same product, but with different cost and capacity. the demand is met by merit of order, and the cost and capacity of each technology may vary. how should i do this in vensim? > I do...

In Vensim you are not supposed to create a graph between two variables as in the graph tool the time is the X coordinate.
I do not know if there is another way to do it.
you must go to Excel to draw a graph of that kind.
Regards.
J.J. Laublé

Hi You need to have Vensim Pro to use vectors or arrays. A variable will have a value from the start of the simulation or the value :NA: which means no value. I you want the value of a to have no value until the time begintime you will define the variable a = if then else (time < begintime,:NA:,the ...

You can too look at Radzicki study on energy at the distance learning course on the SD society web site.
Another possiblity, if you have the time and the monney, is to study at WPI the distance learning course named macroeconomic dynamic.
Regards.
J.J. Laublé

Hi Try the SD mailing list, where you can ask the question. You can subscribe easily on the Vensim Web site. I am currently making a model optimizing price setting and investments, but I have not so far introduced the competition, as I work step by step. Businees Dynamics from Sterman and Strategy d...

Hi Here is attached a simple model, that explains how you can keep an information from one step to the other. One observation, you should simplify your model, and check ir for errors and unit errors. There are too variables with no values that are not visible on the sketch. That does not ease the un...

Hi You must define if your variables, are stocks or auxiliary variables. The market share is obviously a stock (a situation) and some other variables may too be. These stocks will help you model the part of the model that is dependant of the past. It would be too a good idea to send a very simplifie...

Hi, The values associated with a level, are the values at the beginning of the period of time, so you do not get the value at the end of the last period of time. See the model model4 joined to add a last variable to get it. I do not understand your last question. If you add more time steps, you will...

< example? < Thank you J.J. for your reply!!Unfortunately this is my very first SD-model and so it looks as if I need some special < < explanation. If i am honest, I did not get it! So if you have the time and mood to show me an example, I would be < < very thankfull. < I will try to attach my model...

Hi First you nedd to have at least Vensim Pro, as other lower versions do not use subscripts. I tried to construct arrays the way it is explained in the documentation. I have never used it that way. In fact I think that this feature is used only for pasting data from spreadsheet as if you try to use...

Hi If you want to add values only at the last time step, you have to put them somewhere in the meanwhile. This can be done, by putting them in a level, that will keep its value, but you will need Venim pro for that, if you have many values to keep to put them in a subscripted array. Or you can defin...

Hi I have recently received an individual message about my aggregation question which makes me think that i have not been clear enough. Underneath is the answer from my correspondent and my own answer to his message. Is this useful? "To determine whether activities taking place serially can be ...

Hi every body. I am currently working on a model where I need to aggregate the demand of the customers in a minimum of classes while the behaviour of these customers relative to the price is similar. My activity : short term car rental. The criterion of classification is simple: they should have the...

only with one file

the zip file attached did not work, I try with this mail
J.J. Laublé

Hi verery body Here are joined the files attached to the discussion about hows to explain rates to executives and the dt meaning initiated by Kim Warren in the SD mailing list. Anybody interested by this thread should subscribe to the sd mailing list, or consult the archives on this site (Ït does no...

Model attached

one method is to save the auxiliary in a stock. It dos not use any special function and is very transparent. Attached a simplistic model.
Regards.
J.J. Laublé

Hi The two type of lookups are roughly the same. The constant lookup is a lookup function that needs an argument to generate a value. The auxiliary lookup is a lookup where the argument is already settled in the definition of the auxiliary. See the simplistic model joined. When you put different val...

First question. Concerning the two last questions on the Vensim and SD forums about the C compiler, I went to the MSDN microsoft web site and found a Visual C++ .NET 2003 Standard compiler sold at 109 $. Is it the right C compiler to use? Second question about the general use of C with external func...

I tried to unload your zip file, got it but could not open it with Winzip
There must be some reasons.
The administrators should know why.
Regards.
J.J. Laublé