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Difference between consecutive outputs of Simulink clock block is not the fixed simulation step

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Luca Tarasi
Luca Tarasi on 18 Sep 2019
Answered: Chaitanya Mallela on 30 Dec 2020
I have a Simulink model that's run by the following instruction:
SO = sim('schema','StartTime','current_tmin','StopTime', 'current_tmax','SaveState','on','SaveOutput','on', 'OutputSaveName','yout','SrcWorkspace', 'current', 'FixedStep','h_step');
where all the passed parameters have been defined before this instrutcion. Inside the Simulink model there is a block that takes the clock block as input. By printing this block's value when using h_step = 0.001, for example, I get an output that starts as follows:
clock =
0
clock =
5.0000e-04
clock =
7.5000e-04
clock =
1.0000e-03
clock =
0.0015
My question is: why are the time instants not separated by a quantity equal to h_step?
Thank you,
LT.
  1 Comment
Renato SL
Renato SL on 19 Sep 2019
I think the documentation (here) presents a good explanation.
[tl;dr] : "If the model specifies one or more periodic sample times, Simulink chooses a step size equal to the greatest common divisor of the specified sample times. This step size, known as the fundamental sample time of the model, ensures that the solver will take a step at every sample time defined by the model."

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