Ventana software support forum

I think that the reason nobody answers your question must be that it is difficult to understand. You have a delay that is depending on a variable (?) What do you mean by a variable that is not time or size directly? I do not understand at all the last phrase. Join a very simple model with your expla...

When you have loaded the model into one of your directory, it has an *.htm name. You must copy the file or rename it to lake.mdl. When you open that file, it will show you the text format. When in text format if you try to look at it as a sketch (view function then as sketch ) if will tell you that ...

It would help anybody that wants to help you to know the objective of your model first. What are you trying to do? The fact by example that you know the lookup relation between the amount of water in the lake and the surface, questions the necessity to represent the lake as a level. Are there flow i...

I am too interested in putting optimization in simulation and particularly in setting optimal pricing, but can you be more precise about your problem? If nobody understands your problem well enough nobody will be able to help you. Where do you intend to include your linear program, at the end of the...

I have never written an external function in Vensim, but knew that it should work that way. I am glad that there are easier ways to do it. The problem is what can it be useful for? Eventually using the solver in Excel with the programming capability of VBA? The simulation will be slowed down a lot? ...

It would be useful to know what for you are trying to export data during the simulation. If it is to get intermediate results of the simulation, you only have to put the intermediate results in special variables created for that purpose and at the end of the simulation export them to Excel. If you n...

Hi Bob

I had an agerange of 17 instead of 18 in my model in the queue fifo attrib function, and the distribution of the attributes were wrong. This is why I thought the attrib in range was working strangely.
Regards.

J.J.

Hi Bob It is true that in my model, I do not use the queue attrib quantity but the queue attrib in range. Not using the attrib quantity, I do not mind really how it works, but it needs anyhow a much better definition. As to the queue attrib in range I will verify how it works with my full model and ...

Hi Bob Here is the second simplistic model that deals with attrib quantity. I use the same model with 1 car bought each month, no cars sold and I have the graph table that shows number of cars, attrib quantity 1000, 2000 and 3000 That calculates the number of elements whose total attrib is equal to ...

Hi I send a simplistic model for the attrib minimum function, the attrib in range needs more work because it does not work in a model more complicated and I have to transform it in a simple one. The model shows a level of cars with no cars at the beginning running for 7 months, one car being added e...

Hi The min function is still not working with the new version 5.4A. I cannot say if the quantity function is ok due to the definition which is highly imprecise. Ïn the definition there may be more than one result, unless the quantity is cumulated starting with the oldest elements which is not told i...

Christina. If I understand correctly your question, you would like to replace time by population or food, to have sketched the relation between population and food? It will not be anymore a reference mode that sketches the relation of data and time. As for the possibility of doing it, it is more or ...

Hi Wilson Thanks for the help. I have learned too that a subscript if used as a constant holds the number it would have if used as an ordinary subscript starting at one. I used to declare a subscripted variable as I suscript id = 1,2,3,4,5,6,7,8,9,10 for that. Never saw that in the documentation. I ...

Hi every body Is there an easy way to calculate the sums of elements in a vector that change in time? The vector can be an auxiliary or a level. Exemple: the vector has three elements a1(t),a2(t) and a3(t), t being the time. I would like to SIMULTANEOUSLY (meaning in the same time period) have anoth...

Hi every body I use version 5.3 a of Vensim and I use the queue attrib average and queue attrib min functions that I suspect to work incorrectly with small numbers in the queue (1 or 2). Is there a problem with these functions? I have simulated with a spreadsheet the function and it gives different ...

Hi Paul. I am glad that on some rare occasions, on this forum or on the SD list, people talk about business and not all the time about macro economics or macro something else. I think that with the macros, it must be easier to err from the initial objective and to build unrealistic models, the probl...

Hi Rutger. I am not sure at all to be of any help, but trying does not cost anything only my time. Let’s reformulate your problem as I have understood it. Maybe I am wrong. You have built so far a qualitative model that explains the cause, effects and feed back of your problem. Some of the effects a...

HI One way to manage a two dimensional lookup, whatever the kind of dimension (it looks like Time in your case), I have the same case but with price elasticities of different type of products, varying eventually with time which would make it a three dimensional lookup. One way is to simulate the loo...

Hi Did you try the delay conveyor for your in transit problem. It has many advantages. It is a pipeline delay, and you can vary the transit time evey time step and specify the position of the stuff on the conveyor at the start of the simulation as well as inputing every time step a different amount ...

About molecules Hi everybody Last year at the SD conference, somebody talked about a new version of molecules with a lot more of them. When I followed last year the real world distiance course of Jim Hines at WPI , he was already using this new version of molecules in the CD's. What has happened wit...

Hi everybody Last year at the SD conference, somebody talked about a new version of molecules with a lot more of them. When I followed last year the real world distiance course of Jim Hines at WPI , he was already using this new version of molecules in the CD's. What has happened with this version. ...

Have you tried the two options with only 2 offices? Simplifying the problem to get insights is never a lost of time.

J.J. Laublé

Hi bob Thanks for your prompt reply! I will use the get xls look up to get data lookups. As for the dynamic of constants I will temporarily use a dummy variable for each constant or data constant equal to the constant and make reality check to change the values of the dummy variable. It is a bit cum...

Hi every body I have a little problem when I force constants or imported data to new values using reality check. I illustrate this with a simplistic model with one constant = 10 and a variable = 10 * constant = 100, running during 4 years. I check with reality check that if i divide the constant by ...

Why don't you use the time step needed for your inside week constraints for all the model. It is easier to adapt the model to a smaller time step than to work with different parallel time steps.

J.J. Laublé