What this function is set up for is when you have written a big function, that depends on a bunch of smaller functions, that you have also written. Someone wants to borrow the function, but you don't know all the sub functions required to run it. If you run this, it will create a sub directory in the current directory with the name 'funct_nam_dir', and copy the main function, and all the user written sub functions into the directory. You can then create a zip file or just copy the directory and give to the person the complete directory, and they should be able to run the function without any problems.
You must specify any toolbox names you want included (if any), and the main MATLAB install directory, (edit these within the file) as we don't want to include files included in the main MATLAB distribution. This function also assumes that the user created functions are not in the MATLAB install directory.