Ventana software support forum

Administrator wrote:I've got no idea on Mathematica, but there is a function to help,
http://www.vensim.com/documentation/ind ... ?26210.htm

Can you use this to get the strings?

Thanks, that will work out.

Guido

Thanks, I will try that. I had tried working with offset already using something like: strOutput@ToString[ 0, offset ] Unfortunately that did not work out. I even tried to replace the null strings by some other character but failed that. Actually the question is not so much a Mathematica question; r...

Tom (or who else might be able to help), would you have any idea how mutiple null terminated strings might be handled? I have the following problem: The DLL-Function vensim_get_info - to give an example - will return multiple null terminated strings for the type char *buf when asking for say the nam...

Thank you, Tom. I will certainly be looking out for your "double christmas present" and those .vdfx - files!

Best, Guido

OK, found it - careful reading always helps ... The output of a run - and that is what vensim_get_data refers to - will always be single precision thus float[]. Only during a simulation there might be double precision values when using DSS and double precision; this will be addressed by vensim_get_d...

Tom and/or Tony: I am trying to automate the interaction between Mathematica (using the .NET/Link - framework) by writing a Mathematica package that will build upon the VensimDLL. Fortunately defining the DLL function calls is rather straight forward as the type declarations given in C can be used (...

Hi JJ, you seem to make false use of the VECTOR SELECT function since as far as I can see you have put the arguments 1 and 2 of that function in the false order, e.g. you start out with the vector expression ( variable to be summed[sub,tub!] ) and then that is followed by the selection array ( IF TH...

I'll look into the precision issue here. Thanks, Tom. I would suggest that - at least in the case of the delays - the end-user or modeler should not have to worry about numerical issues at such level. I would suggest that something like a chop -function is implemented inside of Vensim so that zeroe...

Hi Tom, I was suprised that even my "beloved" Swiss-Army-Problem-Solver, Mathematica, does give 5.5...E-17 as answer when using machine precision numbers. Mathematica will track the precision and accuracy of numbers though if I understand this correctly. In the end it is machine precision ...

Thanks, Tom.

It is absolutely amazing.

Seems that computers are absolutely stupid, slightly handicapped machines which do their tasks at such speed that humans have no chance catching the error until the task is done.

Kind regards,

Guido

I am a bit astonished to find the following result: I am reading in two percentage values from Excel given as ratio 1 = 70% and ratio 2 = 30% . The third ratio, ratio 3 , is supposed to be the remaining fraction completing the 100% thus zero in this case. The code is naturally rather simple: rawValu...

Tony, I do not know about a fix in 6.1B because we have by now arrived at Version 6.1C in such a short time that I have never been able to even see a working Version 6.1B? As of today I have noted that the table tool show a false value of "01" (which should have been a number close to one ...

Many thanks Tom. Note that there is a slight error in your model. patients seen = MIN(max patients seen,patients waiting) and not patients seen = MIN(max patients seen,patients waiting/average length of appointment) Many thanks Nik Hi Nik, there is indeed no error in Tom's model. A basic considerat...

Obviously my questions above have been somewhat disregarded here. Should I better open a new thread for them?

Guido

While this may go a bit astride, I would like to ponder a bit more regarding the QUEUE FIFO and QUEUE FIFO ATTRIB since they have also been suggested as a possible solution to modeling an aging chain using a cohort & conveyor approach (cf. my post). Question 1: As far as I understand it one coul...

Thanks. Tom, your explanation seems reasonable so this may be the take-away:

Doubling Vensim's precision will cut the modeler's confidence in half and double his confusion.

(After all it does help being able to have a report on what really was caculated in a model ...)

Ok, that header WAS a window (it certainly did not look like one) and resizing it brings back the content.

So it is simply the subscript range issue with the equation editor that still remains.

Thanks so far,

Guido

There seems to be an error in the equation editor (Vensim DSS 6.1a DP) when editing subscripts that I was able to reproduce: I have two subscript ranges Jahrgänge : (J0 - J49) ~~| Altersgruppen : (AG1 - AG10) ~~| Now, I create the constant variable myVariable = 1 using the equation editor and assign...

I keep getting warnings from Vensim DSS DP 6.1A like this one for a model run: WARNING: At 4.875 Below -Fahrzeuge im Alterungsprozess[AG1]-. WARNING: At 9.875 Below -Fahrzeuge im Alterungsprozess[AG2]-. WARNING: At 14.875 Below -Fahrzeuge im Alterungsprozess[AG3]-. WARNING: At 15 Below -Effektiver F...

@Tom and others: I believe I have found what I am looking for: A rather general model structure (rather like a molecule) to represent a delayed process where some kind of leakage or draining takes place. The model is enclosed with this post. Description of the model: The material that arrives at som...

Unfortunately I tend to always use DouplePrecision Vensim DSS - so cheers to puzzlement. I will have to check out the QUEUE ATTRIB functions more deeply now. Regarding the SHIF IF TRUE: I do not like that I have to copy that mechanism down to every attribute of the stocks (which I would have to do, ...

Tom, I have enclosed a model that shows what I would like to have as regular "Conveyor Behavior". I have rebuilt a Conveyor using the DelayFixed. In Synthesim one can switch the Initial Material in the Conveyor between 0 and 1 widget. If there is 1 widget in the conveyor then that will be ...

OK - now I understand the problem - I'll have to ponder a bit. We have a nice solution for this in future Vensim, but it won't be available for a while. Great, Tom, and I am really, really looking forward to the "big release"! ... but what best advise can you offer to keep me a patient an...

What parameters are you using in the model (including TIME STEP)? For me, the linked SimpleConveyorModelCorrTF1.mdl works fine with FractionEventuallyLeaking = 1. Extremely high leak rates do beg the question, why bother with a stock or conveyor, but I agree that the tool should be robust to such e...

I had just written an addendum to a former post suggesting entering a number very close but not equal to one as a potential workaround for a problem related to conveyors (cf. http://www.ventanasystems.co.uk/forum/viewtopic.php?f=2&t=5079#p18401 ). But doing so reveals some bad style in software-...