% Purpose
%    loads the next data file for reading or editing.
%
% Synopsis
%    datafile = mexeps('setnextr')
%    [dirname, datafile] = mexeps('setnextr')
%
% Description
%    It loads the next data file (starting from the second listed 
%    in a pointer file) for reading or editing and returns the data
%    file name.  The function mexeps('openr',filename) or 
%    mexeps('opene',filename) must be called first which opens the 
%    pointer file and also loads the first data file listed in the 
%    pointer file.  
%
%    When one output argument is specified, only data file name not
%    containing directory path will be returned.  When 2 arguments 
%    are specified, both diretory name and file name will be returned.
%    When EOF is reached in the pointer file, this function returns a
%    blank (one single space) to datafile and to dirname if it is
%    specified.
%
% Examples
%    Open a pointer file and load each data file for reading
%
%      infile = 'eps_to_plot.ptr';            
%      currentfile = mexeps('openr',infile); %open pointer file
%					     %and load first data file 
%      while(currentfile ~= ' ')
%        ...
%
%        currentfile = mexeps('setnextr');   %load the next data file
%      end
%
% See Also
%    openr, opene, epsclose
%