function result = boxOfx(width)
%boxOfx return a square made up of the letter x 
%
% consumes: width, a scalar number indicating how many times
%             the letter x should appear
% produces: a square box made up of the letter x 
%
% if x <= 0, an empty string is returned 
%
% Examples:
%    >> boxOfx(3)
%    ans = 
%
%    xxx
%    xxx
%    xxx
%
%    >> boxOfx(5)
%    ans =
%
%    xxxxx
%    xxxxx
%    xxxxx
%    xxxxx
%    xxxxx
%
%    >> boxOfx(-10)
%    ans = 
%           ''
%    >> 
% P. Conrad for CISC106, 10/07/2007
  
  result = []; % set result to the empty matrix
  for i=1:width
    result = [ result ; lineOfx(width) ]; %add a row
  end;

  return;

end % function boxOfx