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

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?

Answer 1

[Thomas Marullo]

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

[Rajan Chalotra]

I too have same problem.

Answer 2

[Ryan Livingston]

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.

Answer 3

[Fayez Alruwaili]

d = zeros (r,c)

d = fun_kk(u);

....