Inverter simulation in Simulink - Time & Space Complexity
When simulating an inverter in Simulink, it's important to know how the time to run the simulation changes as the model size or input length grows.
We want to find out how the simulation steps increase when we use more data or more detailed models.
Analyze the time complexity of the following inverter simulation setup.
% Simulink model setup for inverter simulation
% Sample time and simulation length
Ts = 1e-6; % sample time
Tstop = 0.01; % simulation stop time
% Run simulation
simOut = sim('inverterModel', 'StopTime', num2str(Tstop));
% Extract output waveform
outputWaveform = simOut.get('yout');
This code sets up a simple inverter simulation with a fixed sample time and runs it for a set duration, then collects the output waveform.
In this simulation, the main repeating operation is the simulation time stepping.
- Primary operation: Simulation solver stepping through time increments.
- How many times: Number of steps = total simulation time divided by sample time.
The number of simulation steps grows directly with the simulation duration and inversely with the sample time.
| Input Size (simulation steps) | Approx. Operations |
|---|---|
| 10,000 | 10,000 solver steps |
| 100,000 | 100,000 solver steps |
| 1,000,000 | 1,000,000 solver steps |
Pattern observation: Doubling the simulation time or halving the sample time roughly doubles the number of steps, so the work grows linearly.
Time Complexity: O(n)
This means the simulation time grows in direct proportion to the number of simulation steps.
[X] Wrong: "The simulation time stays the same no matter how long the simulation runs."
[OK] Correct: The solver must process each time step, so longer simulations or smaller steps mean more work and longer run times.
Understanding how simulation time grows helps you design efficient models and predict performance, a useful skill in real projects and technical discussions.
What if we change the sample time to be twice as small? How would the time complexity change?