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setInitialState

Specify initial state for simulation using SimulationInput or Simulation object

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Syntax

s = setInitialState(s,xinit)

Description

s = setInitialState(s,xinit) specifies the initial state xinit on the Simulink.SimulationInput or Simulation object s. Specifying the initial state on a SimulationInput or Simulation object is the equivalent of configuring the Initial state parameter in simulations you run using the object. The model is modified during initialization to use the initial state you specify, and the modifications revert when the simulation completes.

When you specify the initial state for simulation using the setInitialState function, you do not need to specify model configuration parameters using the setModelParameter function or specify the value of the variable that contains the initial state using the setVariable function.

example

Examples

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Open Live Script

Open the model vdp.

mdl = "vdp";
open_system(mdl);

Configure the model to save the final operating point at the end of simulation.

  1. On the Modeling tab, under Setup, click Model Settings.

  2. In the Configuration Parameters dialog box, select the Data Import/Export pane.

  3. On the Data Import/Export tab, select Final states and Save final operating point.

  4. Click OK.

Alternatively, create a Simulink.SimulationInput object to store the parameter values for the simulation. Then, use the setModelParameter function to specify the parameter values to use in the simulation.

simIn = Simulink.SimulationInput(mdl);

simIn = setModelParameter(simIn,"SaveFinalState","on");
simIn = setModelParameter(simIn,"SaveOperatingPoint","on");

Set the stop time for the simulation to 10 seconds. On the Simulation tab, under Simulate, in the Stop Time box, enter 10, or use the setModelParameter function to specify the value of the StopTime parameter for the simulation.

simIn = setModelParameter(simIn,"StopTime","10");

Simulate the model.

out = sim(simIn);

To view the simulation results, double-click the Scope block in the model. The plot in the Scope displays the values of the signals x1 and x2 over the 10-second simulation.

The Scope plot displays the values of the signals x1 and x2 between simulation times of 0 seconds and 10 seconds.

Resume the simulation by using the operating point you saved at the end of the first simulation as the initial operating point for the second simulation.

Get the final operating point from the first simulation from the Simulink.SimulationOutput object out.

vdpOP = out.xFinal;

Specify the operating point as the initial state for the simulation.

  1. On the Modeling tab, under Setup, click Model Settings.

  2. In the Configuration Parameters dialog box, on the Data Import/Export pane, select Initial state.

  3. In the text box, enter vdpOP.

  4. Click OK.

Alternatively, create another Simulink.SimulationInput object to configure this simulation. Then, use the setInitialState function to specify the initial state.

simIn2 = Simulink.SimulationInput(mdl);

simIn2 = setInitialState(simIn2,vdpOP);

Set the stop time for this simulation to 20. On the Simulation tab, under Simulate, in the Stop Time box, enter 20, or use the setModelParameter function to specify the value of the StopTime parameter for the simulation.

simIn2 = setModelParameter(simIn2,"StopTime","20");

Simulate the model again, resuming the prior simulation by starting this simulation from the final operating point saved in the first simulation.

out2 = sim(simIn2);

The plot in the Scope window updates to show the data from this simulation. The time axis starts at 0 and goes to the simulation stop time of 20. Because this simulation started from the initial operating point from the first simulation, which ended after 10 simulation seconds, the plot shows the values of the signals x1 and x2 only between simulation time 10 seconds and 20 seconds.

The Scope plot shows the values of the signals x1 and x2 between simulation times of 10 seconds and 20 seconds.

Input Arguments

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Simulation specification or simulation in which to specify initial state, specified as a Simulink.SimulationInput object or a Simulation object.

A SimulationInput object represents a simulation specification that includes the initial state, external inputs, model parameter values, block parameter values, and variable values to use in the simulation. When you specify the first input argument as a SimulationInput object, you must specify the SimulationInput object as a return argument.

The Simulation object represents a simulation and provides an interface for controlling and interacting with the simulation. When you specify the first input argument as a Simulation object, specifying the Simulation object as a return argument is optional.

Example: simin = setInitialState(simin,xinit) specifies the initial state xinit in the simulation configuration stored on the SimulationInput object simin.

Example: sm = setInitialState(sm,xinit) specifies the initial state xinit for the simulation represented by the Simulation object sm.

Initial state or operating point, specified as a Simulink.op.ModelOperatingPoint object, a Simulink.SimulationData.Dataset object, or a structure that matches the Structure or Structure with Time logging format.

Example: simin = setInitialState(simin,xinit) specifies the initial state xinit in the simulation configuration stored on the SimulationInput object simin.

Example: sm = setInitialState(sm,xinit) specifies the initial state xinit for the simulation represented by the Simulation object sm.

Output Arguments

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Simulation specification or simulation with initial state added or modified, returned as a Simulink.SimulationInput object or a Simulation object.

When you use the setInitialState function to specify the initial state on a SimulationInput object, you must specify the SimulationInput object as the return argument.

When you use the setInitialState function to specify the initial state on a Simulation object, assigning the return argument is optional.

Version History

Introduced in R2017a

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See Also

Objects

Functions

Model Settings

Topics