For one of my course project I started implementing \"Naive Bayesian classifier\" in C. My project is to implement a document classifier application (especially Spam) using huge
Try computing the inverse 1/p. That gives you an equation of the form 1 + 1/(1-p1)*(1-p2)...
If you then count the occurrence of each probability--it looks like you have a small number of values that recur--you can use the pow() function--pow(1-p, occurences_of_p)*pow(1-q, occurrences_of_q)--and avoid individual roundoff with each multiplication.