octave: Private Functions

 
 11.9.3 Private Functions
 ------------------------
 
 In many cases one function needs to access one or more helper functions.
 If the helper function is limited to the scope of a single function,
 then subfunctions as discussed above might be used.  However, if a
 single helper function is used by more than one function, then this is
 no longer possible.  In this case the helper functions might be placed
 in a subdirectory, called "private", of the directory in which the
 functions needing access to this helper function are found.
 
    As a simple example, consider a function ‘func1’, that calls a helper
 function ‘func2’ to do much of the work.  For example:
 
      function y = func1 (x)
        y = func2 (x);
      endfunction
 
 Then if the path to ‘func1’ is ‘<directory>/func1.m’, and if ‘func2’ is
 found in the directory ‘<directory>/private/func2.m’, then ‘func2’ is
 only available for use of the functions, like ‘func1’, that are found in
 ‘<directory>’.