title: calculating user defined formulas (with c++)
body: <p>We would like to have user defined formulas in our c++ program.
  e.g. The value <em>v = x + ( y - (z - 2)) / 2</em>. Later in the program the user would define x,y and z -> the program should return the result of the calculation. <br />Somewhen later the formula may get changed, so the next time the program should parse the formula and add the  new values. <br/><br/> Any ideas / hints how to do something like this ? <br/><br/> So far I just came to the solution to write a parser to calculate these formulas - maybe any ideas about that ?</p>