Why is my variable undefined when using parsim?

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MathWorks Support Team 2018-8-30

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https://ww2.mathworks.cn/matlabcentral/answers/446894-why-is-my-variable-undefined-when-using-parsim

编辑： MathWorks Support Team 2025-11-10

I have a simulink model that runs when I'm not running it in parallel, but it will not run in parallel. In the function that invokes my model I create a class handle object and store it in the base workspace. From within the model I have a Matlab function that calls a function of the object by evaluating it in the base workspace. In parallel mode I get an error saying that this object handle is undefined. But it works fine if I don't run it in parallel mode.

I've created a simple model that illustrates the problem (you will need to include the files TestClass.m and TestObjSim.slx in the same directory):

objH = TestClass(1);
assignin('base','objH',objH);
% This works:
simOut = sim('TestObjSim');
% Running in parallel doesn't work:
in = Simulink.SimulationInput('TestObjSim');
simout = parsim(in,'TransferBaseWorkspaceVariables','on');
disp(simout.ErrorMessage);

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Answer 1

MathWorks Support Team 2025-11-10

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/446894-why-is-my-variable-undefined-when-using-parsim#answer_362650

编辑：MathWorks Support Team 2025-11-10

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The reason the you see the error is because the base workspace is not shared among the workers, To make sure that each worker has access to everything, I would recommend create an initialization function that can be called by each worker to load the data including the class into the worker's base workspace.

For example,

1) Define a function in loadObject.m.

function loadObject()
    objH = TestClass(1);
    assignin('base','objH',objH);

2) Load the function in all workers and run parsim:

% Load object in all workers
parfevalOnAll(@loadObject,0);
% Run parallel simulation
in = Simulink.SimulationInput('TestObjSim');
simout = parsim(in,'TransferBaseWorkspaceVariables','on');