Search found 15 matches

by grayven87
Sun Jun 02, 2019 6:05 am
Forum: Vensim
Topic: Distribution Help!!!
Replies: 2
Views: 1636

Distribution Help!!!

Hi everyone,

I am running a model that requires a Beta distribution with parameters 0.62 and 0.82 but apparently with Vensim, more parameters like shift and scale are needed.Can anyone please guide me through the calculation method for these extra parameters so I can run the model successfully?
by grayven87
Tue Apr 30, 2019 9:47 am
Forum: Vensim
Topic: Floating error
Replies: 7
Views: 4201

Re: Floating error

Hi everyone my model is giving me this error for a flow variable of mine at time 0 whenever I try to run it.can anyone help me with this issue and please state: -Is the issue with the variable equations? -Should I be looking at the cause diagrams and fix that? -Could it be related to the whole model...
by grayven87
Tue Apr 30, 2019 8:55 am
Forum: Vensim
Topic: Using Time Steps
Replies: 5
Views: 2486

Re: Using Time Steps

How about: Is First Run = 0 ~ dmnl ~ switch indicating whether or not this is a first run Defined value var 1 = ... ~ something Initial var 2 = ... ~ something Var 2 = IF THEN ELSE( is first run, Initial var 2, functionOf(Defined value var 1) ) If you tell us something about the problem you're tryi...
by grayven87
Sun Apr 28, 2019 9:57 am
Forum: Vensim
Topic: Using Time Steps
Replies: 5
Views: 2486

Re: Using Time Steps

tomfid wrote: Fri Apr 26, 2019 1:50 pm Not following this ... if variable #2 only has an initial value, how can new values be measured?
My aim is for variable no.2 to have an initial value just for the first time the model is run, other then that I want it to have a function that is defined and is depended on variable no.1.
by grayven87
Sun Apr 28, 2019 7:55 am
Forum: Vensim
Topic: Defining Units
Replies: 4
Views: 2128

Re: Defining Units

I've been defining the units but for defining the cost of hiring, I had to use 200*"staff no." and the software's unit checking part gives me an error that the unit of money for cost of hiring isn't correct... Is there any way I could get rid of this error besides defining a new variable f...
by grayven87
Sun Apr 28, 2019 7:43 am
Forum: Vensim
Topic: Defining Units
Replies: 4
Views: 2128

Re: Defining Units

Definitely - percent is important because it's easy to inadvertently mix % and fractions. Define a variable called "100 percent" with units of "percent" and use that to convert between the two. Something like: "100 percent" == 100 ~ percent birth rate = 2.3 ~ percent/y...
by grayven87
Fri Apr 26, 2019 12:15 pm
Forum: Vensim
Topic: Questions about random Weibull
Replies: 15
Views: 6874

Re: Questions about random Weibull

tomfid wrote: Thu Apr 18, 2019 6:16 pm Here are three different parameterizations, using terminology from NIST, Wikipedia and Wolfram Mathworld:
RANDOM functions.mdl

Thanks a lot!! :)
by grayven87
Fri Apr 26, 2019 12:14 pm
Forum: Vensim
Topic: Defining Units
Replies: 4
Views: 2128

Defining Units

Hi everyone

I have a homework model and we are told to define the units.My question is, Should we add units for binary and Dimensionless variables, like numbers and percents?

Would be great if you guys could help me out!
by grayven87
Fri Apr 26, 2019 12:02 pm
Forum: Vensim
Topic: Using Time Steps
Replies: 5
Views: 2486

Using Time Steps

Hi everyone A homework model in vensim that I have starts from a variable no.1 that depends on the value of variable no.2, but variable no.2 only has an initial value and after each run time, a new value is measured for it.I unfortunately have problems running the model. My questions are: Is it even...
by grayven87
Mon Apr 22, 2019 3:38 am
Forum: Vensim
Topic: a Question about units
Replies: 4
Views: 3166

Re: a Question about units

Hi everyone

Can someone tell me how I can access the current units defined in Vensim PLE and choose from them? and how I can edit the units list just for one model?
by grayven87
Sat Apr 20, 2019 9:47 am
Forum: Vensim
Topic: Run a model but simultaneous equations involving
Replies: 1
Views: 1486

Run a model but simultaneous equations involving

Hi everyone I seem to be having the same error in regards to my initial variables, and they happen to also be auxiliary variables with initial values.could someone please explain a level variable more and tell me whether the error is usually from the variables or it could also be from the relations ...
by grayven87
Thu Apr 18, 2019 2:08 pm
Forum: Vensim
Topic: Questions about random Weibull
Replies: 15
Views: 6874

Re: Questions about random Weibull

Hi Tomfid I had tried the sample model and have also studied and thoroughly read your help page before but I still had the same problem.I think it would be better if you could provide me with some additional information about what the standard parameters of this function in Vensim define.I think tha...
by grayven87
Wed Apr 17, 2019 8:05 pm
Forum: Vensim
Topic: Questions about random Weibull
Replies: 15
Views: 6874

Re: Questions about random Weibull

Terminology for the Weibull distribution is not well standardized, and most sources don't use alpha and beta. Can you give us a reference you're trying to match? well I'm trying to use the function for the weibull distribution that I only have the two following parameters of alpha , the shape param...
by grayven87
Wed Apr 17, 2019 7:52 pm
Forum: Vensim
Topic: Random Weibull Distribution Parameters
Replies: 1
Views: 1393

Random Weibull Distribution Parameters

Hi everyone I have a problem with the Random.Weibull function in Vensim: RANDOM WEIBULL(rW minimum, rW maximum, Weibull shape S, Weibull shift, "Weibull scale (mean)", seed) I currently have to run a problem which only has alpha and beta and I couldn't understand which parameters in the fu...
by grayven87
Wed Apr 17, 2019 7:47 pm
Forum: Vensim
Topic: Questions about random Weibull
Replies: 15
Views: 6874

Re: Questions about random Weibull

Hi everybody

I have a problem regarding the random weibull distribution in vensim, can anybody tell me for which parameters in the distribution description I should enter beta and alpha?