Why does Simulink throw an error about variable size matrix from my MATLAB Function block?

Why do I received the following error in Simulink?

Data 'x' is inferred as a variable size matrix, while its properties in the Model Explorer specify its size as inherited or fixed. Please check the 'Variable Size' check box and specify the upper bounds in the size field.

Component:MATLAB Function | Category:Coder error

Simulink cannot determine sizes and/or types of the outputs for block 'MATLAB Function' due to errors in the block body, or limitations of the underlying analysis. The errors might be inaccurate. Fix the indicated errors, or explicitly specify sizes and/or types for all block outputs.

Component:MATLAB Function | Category:Coder errorOpen

Simulink cannot determine sizes and/or types of the outputs for block 'MATLAB Function' due to errors in the block body, or limitations of the underlying analysis. The errors might be inaccurate. Fix the indicated errors, or explicitly specify sizes and/or types for all block outputs.

Component:Simulink | Category:Model error

Error occurred in 'example/MATLAB Function'.

Component:Simulink | Category:Model error

My MATLAB function only has these few lines of code:

function [x] = fun(A)
y = max(A);
x = find(A==y,1);

Answer 1

[MathWorks Support Team]

This error occurs because the "find" function always returns a variable-length vector.

If you do not want to change the properties of the variable "x" in MATLAB Function to be variable sized as suggested in the error message, you can change the MATLAB Function to not use "find".

For example,

function [x] = fun(A) 
[y, x] = max(A);