question

Amanda Prado avatar image
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Amanda Prado asked Jason Lightfoot commented

How create random numbers?

Hello,


Could someone help me with a question? My situation is as follows:


I need my source to create 5000 products in a given period of time. There are 8 product models in total that arrive randomly, and it is not possible to determine the probabilities of arrival at this time. The products arrive randomly and not uniformly. It is really unpredictable.


Only one of the models arrives with a minimum quantity of 2000 units, the other 7 models are unpredictable.


With the DUNIFORM distribution it is not possible to do this, and also with the empirical distribution, because I do not know the probabilities.


Is there any way to do it via script?


Thank you very much!

FlexSim 24.2.1
flexscriptdistributionsrandom
5 |100000
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2 Answers

Felix Möhlmann avatar image
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Felix Möhlmann answered Jason Lightfoot commented

Generating a random number without an underlying distribution is not possible. If such a distribution is not known, I guess a decent approach would be to test the model against different distributions (empirical or otherwise) that seem 'reasonable' to make sure the system can handle many different situations.

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Amanda Prado avatar image Amanda Prado commented ·

Thanks for your explanation.

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Jason Lightfoot avatar image Jason Lightfoot ♦♦ Amanda Prado commented ·

Arrivals are often generated using a Poisson process, so if you know the interarrival time you can generally use the negative exponential distrubution with the mean inter-arrival time as the parameter to mimic the arrival process. This is memoryless, so the time to the first arrival can also be negative exponential with the same mean.

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Joerg Vogel avatar image
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Joerg Vogel answered Amanda Prado commented

You can do it with two datetime sources in process flow. One creates in a time interval 2000 items randomly distributed items. These items get a unique identifier. A second datetime source creates 3000 items and assigns randomly identifiers for example by a duniform distribution.

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Amanda Prado avatar image Amanda Prado commented ·

Joerg Vogel, could you give me an example how can I do that ?

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Joerg Vogel avatar image Joerg Vogel Amanda Prado commented ·

@Amanda Prado, sure.

DateTime_sources.fsm

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datetime-sources.fsm (33.6 KiB)
Amanda Prado avatar image Amanda Prado Joerg Vogel commented ·
Thank you very much !
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