Ventana software support forum

Hi Suppose that you have a constraint on a variable A like A <= 0 like you find in many optimization problem and want to find the maximum of C. The solution is to create another variable like B = if then else (A<= 0,0,-100000) and to optimize the variable D = C + B. When Vensim will look for the max...

I do not think that your problem is complicate. It needs to be well undestood. One question. What does exactly describes the table batch is prerequisite? Does it mean that once a batch has finished its work, it is necessarily the next one that takes the next job. After batch one has finished, it is ...

Why is raw material depending on the kind of batch. Ï understand that each product needs specific kind of raw material but why do batches.
J.J. Laublé

Can you define precisely what the batches are? Are there productions units,
stocks of unfinished products waiting to be finished?
I think it it necessary to better formulate your problem, if you want somebody to help you.
I do not understand exactly what the batches are.
Regards.
J.J. Laublé

looking back at your model, I would advice that you first simplify it extremely so that there is only one stock and two or three auxilaries or rates. And then once done, step by step refine it. I suppose you have some more years to live, and plenty of time to make things more complicated if needed. ...

Hi Esc I loaded the model, but it has unfortunately model and unit errors and cannot be run. It is a good practice to try first to have no model errors and dimensions (unit) defined. It helps the understanding of the model. When one checks the model, it points out many errors for instance the first ...

you can do this two ways. Cliking on the com button and cliking on the variable name on the sketch and changing the name of the variable. it will automatically change the name of the variable everywhere. If you have no com button, you can change the name of the variable with the equations button. Wh...

Hi

Sorry for the trouble.
The model was effectively blank.
Joined a zip file that must be good or at least that I have tested, unloaded in a new place, and run.
Tell me if you have any problem.
Regards.
J.J. Laublé

Hi you must first unzip the tank.zip file using winzip. You should get three files named tankfilling.mdl, rainfall.dat and rainfall.vdf. Have you got these files? The tankfillink model should word with the PLE edition. If you cannot load the model, if you open it with a text editor like word, do you...

What do you mean by van't (or probalby can't) see the model?
The trial version of what?
Regards.
J.J. Laublé

Hi Joined a model that should work. The data are in a text or ascii file named rainfall.dat, that has been converted by vensim to rainfall.vdf. You can change it with any text editor, but must convert it again (goto model on the sketch and from .dat format). Vensim knows that the data come from the ...

Hi There is a course on macroeconomic dynamics offered in distance course by the W.P.I. that you can find on the Web site www.systemdynamics.org SD 565. Macroeconomic Dynamics. There are three parts to this course. The first acquaints a student with dynamic macroeconomic data and the stylized facts ...

Hi

Can you just send your model or a model simplified. Il will be easier to spot the problem.
Regards.
J.J. Laublé

Why not join a very simplistic model summarizing the problem. It will have three benefits. After having simplified the problem, you may find the solution by yourself. It will ease the understanding of the problem. It will increase the people susceptible to study your problem, easier to understand an...

Hi Lidygal First you should correct the units error. I never run a model that has any unit error in it, unless warnings. Secondly the model when run gives the following error: WARNING: At 2003 Above -Impuestos- computing -Impuestos por pagar-. Meaning that the lookup gets value as input higher than ...

Thank’s Bob

What is the average percentage of improvement when compiling and is there a substantial increase of speed to prefer one compiler to another?
Thanks in advance and best regards.
J.J. Laublé.

Hi everybody I have two questions. 1. Is it possible when using the optimizer to have a report that traces only the different best pay offs, with the number of the simulation and the new pay off? I need this because some of my optimizations, taking a long time , if I have to check the *.rep Or *.out...

Hi

joined a model that uses a sort of Kutta Runge technic of integration, which is a better approximation then the Euler one, where you would take current level instead of (current level + previous level) / 2.
Regards.
J.J. Laublé

Hi If you look at the definition of the vector elm map it has at the end an example of how to get the value of an element in a three dimensions array, using the vector elm map function. This explains exactly the exact offset of any element in this array. If you cannot transform a three dimensionnal ...

Hi

joined the model that transforms an array to a vector and retransforms the vector back to an array.
J.J. Laublé

Joined the formulation back
Regards.
J.J. Laublé

Hi The equation is VECTOR ELM MAP( Array[n1,m1] , (subscript3 - 1)) The value subscript3 - 1 is the offset. The offset is the number of positions starting from the beginning of the array needed to be translated through to get to the value corresponding to the vector. So for instance for the first va...

Here is joined a very simple model that transforms an array with two subscripts and 6 values into a vector of one subscript with the same number of values.
Regards.
J.J. Laublé

There are other functions that work only with the last subscript, for instance ordering an array on one subscript (Vector sort order). If you want to work on several subscripts, the solution is to transform two subscripts into one and after having done the job, retransform if necessary the one subsc...

Hi

Arrays or vectors are not implemented in Vensim PLE.
You must then use Bob's solution where you make the rate dependant from other auxiliaries and will change with the time.
Regards.
J.J. Laublé