function read_file(filename)
%
% Read the contents of the given file.
%   Print out each line from the file onto the screen.
%   
% Arguments:
%      
%         filename          (input)  name of disk file to read
%                   

  % first, we try to open the file for reading
  fid = fopen(filename, 'r');
  if (fid == -1) 
    error('read_file: cannot open file for reading');
  end

  % read each line from the file, printing it to the screen as we go
  done_yet = 0;
  while (done_yet == 0)

    line = fgets(fid);
    if (line == -1) 
      done_yet = 1;
    else
      % we don't need to add an '\n' at the end, because the FGETS
      %   function keeps the newline at the end of the string it returns.
      fprintf(1, '%s', line);
    end
    
  end

  % remember to close the file before we return;
  fclose(fid);