added fractions and RNG::trial

src/rng.cc

@@ -32,6 +32,10 @@ int RNG::get_curr_rand_num() const {
         return curr_rand_num;
 }
 
+bool RNG::trial(fraction &psuccess) {
+        return (rand() % psuccess.denominator) < psuccess.numerator;
+}
+
 template<class T> T &RNG::get_rand_in_vector(const std::vector<T> &vec) {
         curr_rand_num = rand();