How to call extrisic m-file contains function handle in SIMULINK user-defined MATLAB function?

Question

LEE YUMY 2015-3-2

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https://ww2.mathworks.cn/matlabcentral/answers/181000-how-to-call-extrisic-m-file-contains-function-handle-in-simulink-user-defined-matlab-function

回答： Fayez Alruwaili 2021-1-29

I am trying to understand how to call extrisic m-file contains function handle in SIMULINK user-defined MATLAB function. Here I wrote a test to call an extrisic m-file named "fun_kk" in my SIMULINK user-defined MATLAB function as below:

***********************

function y = actuator(u)

coder.extrinsic('fun_kk')

d = fun_kk(u);

y = d;

**************************

And the "fun_kk" is:

*****************

function d = fun_kk(u)

d = sqrt(@(u)u^2);

*****************

After runnung SIMULINK by giving a contant input u, the error message apears:

 Function output 'y' cannot be an mxArray in this context.
 Consider preinitializing the output variable with a known type.
 Function 'MATLAB Function' (#159.9.10), line 1, column 10:
 "y"
 Launch diagnostic report.

Could anyone please help me to solve this problem?

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Answer 1

Thomas Marullo 2015-12-4

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Have you solved this problem? I am having the same problem.

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Rajan Chalotra 2017-2-14

I too have same problem.

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Answer 2

Ryan Livingston 2017-2-14

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https://ww2.mathworks.cn/matlabcentral/answers/181000-how-to-call-extrisic-m-file-contains-function-handle-in-simulink-user-defined-matlab-function#answer_254707

编辑：Ryan Livingston 2017-2-14

You can see the explanation of this here:

https://www.mathworks.com/help/simulink/ug/calling-matlab-functions.html#bq1h2z9-46

Namely, the code generator can't know the output type of the extrinsic function call. You can pre-assign the output to tell it what the type, size, and complexity are:

coder.extrinsic('fun_kk')
y = 1; % assuming real scalar double output for fun_kk
         % change to match the expected type, size, complexity
y = fun_kk(u);

Now, fun_kk only uses constructs which are supported for codegen (anonymous functions are supported as of R2016b) so there's no need to use coder.extrinsic. Just call fun_kk, omit the coder.extrinsic, and everything should work out.