What is the inversion of the Shunting Yard algorithm?

Dijkstra's Shunting Yard algorithm is used to parse an infix notation and generate RPN output.

I am looking for the opposite, a way to turn RPN into highschool-math-class style infix notation, in order to represent RPN expressions from a database to lay users in an understandable way.

Please save your time and don't cook up the algorithm yourselves, just point me to textbook examples that I can't seem to find. Working backwards from the Shunting Yard algorithm and using my knowledge about the notations I'll probably be able to work up a solution. I'm just looking for a quick shortcut, so I don't have to reinvent the wheel.

Oh, and please don't tag this as "homework", I swear I'm out of school already! ;-)

From stackoverflow Hanno Fietz

• google search, 3 results

  From Steven A. Lowe

• Since RPN is also known as postfix notation, I tried googling convert "postfix to infix" and got quite a few results. The first several have code examples, but I found the RubyQuiz entry particularly enlightening.

  From Bill the Lizard

• If you're not worried about removing redundant parentheses, then the following Lisp code will work:

  (defun rpn-to-inf (pre)
    (if (atom pre)
        pre
        (cond ((eq (car (last pre)) 'setf)
           (list (rpn-to-inf (first pre)) '= (rpn-to-inf (second pre))))
          ((eq (car (last pre)) 'expt)
           (list (rpn-to-inf (first pre)) '^ (rpn-to-inf (second pre))))
          (t (list (rpn-to-inf (first pre)) 
            (car (last pre)) 
            (rpn-to-inf (second pre)))))))
  

  From Paul Reiners