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Patrick Zweekhorst avatar image
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Patrick Zweekhorst asked Mischa Spelt edited

What changed in dempirical between FlexSim 16.2 and FlexSim 17.0?

Hi,

I have a model which I updated from 16.2 to 17.0. I thought the outcomes should be exactly the same, but they are not. I noticed a difference in the outcomes of the dempirical function I use. Attached are two sample models ( dempirical16.fsm and dempirical17.fsm ) that execute the same script. One model is in FlexSim 16.2 and the other in 17.0. The results of the dempirical function are clearly not the same. What changed between 16.2 and 17.0 that causes this behavior?

Tanks in advance,

Patrick

FlexSim 17.0.1
random streamdempirical
dempirical16.fsm (12.6 KiB)
dempirical17.fsm (12.3 KiB)
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Mischa Spelt avatar image Mischa Spelt commented ·

It seems that the default stream is different between the two versions: in one (I think it was 2016) it samples from stream 0 when the last parameter is omitted, like all the other statistical functions; in 2017 it suddenly defaults to stream 1. @anthony.johnson bug? :)

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1 Answer

Joerg Vogel avatar image
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Joerg Vogel answered Joerg Vogel edited

If you had set a different random stream each time you use a statistical distribution, as it is recommended, the results would be the same for the model in Flexsim 16 and 17.

If someone uses every time the same random stream for most or all statistical distributions the results maybe look right but in fact you get systematical errors in the results.

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