Oops, nice catch, though I would expdect you to spot such an error :). I can only say that mine does work, though with a rather less competitive performance. It's just like me to take something as dandy as the Schwartzian Transform and use it wrongly. Thanks for the correction, it will never happen again, I promise. ++ for the removal of chomp and the additional of the extra pair of capturing parentheses. Why didn't I think of that?