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Is there anyway to force Anylogic to use a fixed time step when simulating a system dynamics model?

I am converting my System Dynamics model from Vensim to Anylogic in order to add additional capabilities available in Anylogic. In Vensim, I used Euler integration with a chosen time step that was short enough to overcome possible inaccuracies. The model worked well. In Anylogic, I have the diferential equation numerical method set to Euler and I try to use the same time step but it appears it is adjusting the time step and changing how the model responds. Changing to RK4, the model performs even more erratically.

I checked the Anylogic time step by looking at the output of the engine: getEngine().getNextStepTime()-time()

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1 Answers

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It's not possible... I answered a similar question a while ago where I explain why Vensim tricks you into thinking your model is correct by using large time steps... check it out here:

Systems Dynamics in AnyLogic - Fibonacci sequence