Rui - it may be helpful to attach the files so that we know what you code you have. I suspect that you have at least one m-file that calls one or more MEX functions that are in C-files i.e. files with a c extension (written in the C programming language).
I have a Mac as well, and it is easy to build the MEX-functions from C/C++ as per the documentation found at the link MEX.
To setup, you need a C/C++ compiler. In the MATLAB Command Window, type
mex -setup C
What do you see? When I run this command, I observe
MEX configured to use 'Xcode with Clang' for C language compilation.
You may need to install Xcode in order to get a similar compiler. Once a compiler has been chosen, you can build the MEX-files. Change to the directory that contains the *.c files and type the command (in the MATLAB Command Window) to build the MEX-function
mex functionName.c
where functionName is the name of the function/file. You will either observe errors or see that it built successfully
Building with 'Xcode with Clang'.
MEX completed successfully.
In your folder, there will now be a file similar to functionName.mexmaci64.
Repeat the above for each C-file.
Once completed, you can call each MEX-function from within the MATLAB code as if it were a MATLAB function
% call functionName to do something
Z = functionName(A,B);
so long as you provide inputs (and assign outputs) as directed by the function signature.
Try the above and see what happens!
