MATLAB code runs but it throws error once compiled.

Hi, everyone. I made a program that seems to work as I expected (when I run .m file from the editor), but when I try to use it in the GUI/compiled version, it crashes. I debugged it and as I can see, the problem comes from calling a function that uses the legendreP() built-in function. I don't know how to fix, since that's the only built-in functions that fails.

Thank!