conversion from infix to postfix, and, compilation of postfix for eval

Hi,

I was trying to write a graph plotting program with c++. I need to convert the infix expression from user to postfix expression for quick evaluation. However, the evaluation of postfix is kind of interpreted, and thus kind of slow for evaluating huge number of values. Say if I plot an implicit function the penalty is quite huge. Is there a way that I can compile the infix expression from my running graph plotting application for high speed evaluation.

How can this be best done ?