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simulationanylogic

Using varying lambda with interarrival time while receiving same arrivals across models

I have learned from my previous question “Get the same arrival rate across models” that for two models with the same arrival rate input, I can get the exact same arrivals generated in both models by setting the source block in both to “Interarrival time” and in the code, use exponential(lambda, 0, rand) where rand is a user-defined random number generator (RNG), for example, Random rand = new Random(1234). If prior to setting the source block to “Interarrival time” I had it set to “Rate Schedule” in which the schedule is of type rate that is provided from the database and in my case the rate (lambda) is not constant, it depends on the time of the day, how can I overcome this when setting the source block to “Interarrival time”?

Solution

  • Since it is not possible to set a seed for the arrival rate, you'll need to use interarrival times instead in your source.

    However, since you also need to vary the interarrival time based on the time of day, you should write a function that returns different exponential random variables depending on the time of day and use that as your interarrival times.

    Here is how I did that in AnyLogic:

    Source block

    function

    And I made a quick plot of how many injections were occurring per hour just to verify that the rates are actually changing.

    plot