Performance Problem in Simulink (why is it slower than matlab?)

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Akbar
Akbar 2018-4-10
编辑： Akbar 2018-4-12
I have compared Solutions to the same ODE in matlab and simulink. Simulink took 7.6 sec. while ode15s in matlab took 1.4 sec. to solve. What is the reason for this time difference? FYI: I used the same number of time steps in both cases. And simulink model was run from matlab, using 'sim' function.
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Akbar
Akbar 2018-4-12
Matlab code:
for i = 1:100
[t{ind},X{ind}] = ode15s(func,0:.1:10,X0);
end
Simulink code:
for i = 1:100
simOut = sim(model_file,'SimulationMode','normal');
outputs = simOut.get('yout');
outI = outputs.get('X');
t{ind} = outI.Values.Time;
X{ind} = outI.Values.Data;
end

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回答（1 个）

Steven Lord
Steven Lord 2018-4-10
Which solver did you use when you simulated your system? Did you leave the selection up to Simulink?
The ode15s solver in MATLAB is a stiff solver while ode45 is not. So if your simulation used ode45, to compare apples and apples you'd want to compare that with solving the system in MATLAB using ode45 (or switch both to use a stiff solver.)
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Akbar
Akbar 2018-4-12
编辑：Akbar 2018-4-12
In simulink I used: "VariableStepAuto". I have just tried ode15s on both (with the same stepsize: 0.1) and still got a significant difference in time. Apart from that, simulink and ode45 have failed to solve the System correctly, it deviated from the true solution.
ode15s: 0.8488
ode45: 0.088538
simulink (normal): 13.2582

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