matlab standalone desktop app stuck in syms command

Hi there, I encountered a problem developing a matlab app.

When I debug in the matlab app designer, no problem occurred, so I generated the standalone desktop app.

However when I run the deployed the standalone desktop app, it appears that it got stuck somewhere, not being able to display the right results.

Since a standalone app is quite hard to debug, I have to write a log file for the app and the self-written class invoked, to check which line the app had stopped. (BTW is there a more efficient way to debug in a situation like this?)

I found the app stopped in the self-written class invoked. The context code is as follows.

            fid = fopen('D:\Matlab App License\create_polylog.txt','w+');
            fprintf(fid,"0\r\n");
            n = obj.order;
            obj.coef_table=string(zeros(n+1,4));
            obj.index = [];
            fprintf(fid,"1\r\n");
            syms 'p%d' [1,n]
            syms x y p0
            poly = p0;
            fprintf(fid,"2\r\n");     

where the log file result is,

            0
            1

It seems the app stops trying to create a syms object? Is there anything I can do to debug this?

Thanks a lot.

Answer 1

[Steven Lord]

Creation of symbolic expressions using sym or syms is not supported in MATLAB Compiler as stated on this documentation page. Perform the symbolic calculations and generate a MATLAB function file using matlabFunction in MATLAB then include the generated function file in your deployed app.

[Wong Slocked]

Thank you for you reply.

Does this mean that I'll need to generate the function in advance and save it in some sort of a map, then invoke when needed?

[Steven Lord]

Use isdeployed to determine if the code is running as a deployed application or not. If it is you cannot use sym or syms and will need to run an alternate code. One way to create that alternate code as a separate function file is using matlabFunction ahead of time.

[Wong Slocked]

Thanks again.