If the element of the bus is put as an input to the matlab function

Question

가은 최 2022-4-5

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https://ww2.mathworks.cn/matlabcentral/answers/1689059-if-the-element-of-the-bus-is-put-as-an-input-to-the-matlab-function

回答： arushi 2024-9-6，6:53

在 MATLAB Online 中打开

We designed simulink as shown in the picture above.

Matlab function wrote the following code, but it doesn't work.

How can we solve this error?

function y = fcn(u)
element.u1 = u.x;
element.u2 = u.y;
element.u3 = u.dy/dt;
y = 4 * element.u1 - 4 * element.u2 - 4 * element.u3;
end
Error 
Property 'x' is not recognized as valid.
Function 'MATLAB Function' (#36.34.37), line 3, column 14:
"u.x"

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Answer 1

arushi 2024-9-6，6:53

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1689059-if-the-element-of-the-bus-is-put-as-an-input-to-the-matlab-function#answer_1511879

在 MATLAB Online 中打开

Hi 가은 최,

I understand that you have elements in a bus, and you want to access these elements inside a MATLAB function block.

The DOT(.) notation you are currently using to access elements inside MATLAB function block only works with non-virtual busses and by default the Bus Creator block outputs virtual bus. To access elements from virtual bus you can use indexing. Change your code as follows:

function y = fcn(u) 
    element.u1 = u(1);   % x 
    element.u2 = u(2);   % y  
    element.u3 = u(3);   % dy/dt 
    y = 4 * element.u1 - 4 * element.u2 - 4 * element.u3; 
end 