P-files contain only the parsed MATLAB code. They do not include the help or other comments from the original file. When you use the HELP command, MATLAB looks for a file with the specified name and a .M extension. In order to include help with your P-files, you will need to include a separate .M containing the help comments. If both a .M and .P file exist, MATLAB will call the P-file for execution, so the .M file only needs to contain the help comments.
The following function extracts the help informations from a MATLAB function and saves it into a new file. The help information will be saved in a file with the same name but using an underscore as a prefix.
function help2file(fname)
% HELP2FILE extract the help informations from a MATLAB file and save it separately
% the help information will be saved with the same name but using an underscore as a prefix.
mhelp = help(fname);
fname = [strrep(fname,'.m','') '.m'];
%
fid = fopen(['_' fname],'w');
fwrite(fid,['%' strrep(mhelp,sprintf('\n'),sprintf('\n%%'))]);
fclose(fid);
