10 #include "boost/random.hpp"
12 typedef unsigned int seedType;
13 typedef boost::mt19937 engine_type;
14 typedef boost::gamma_distribution<> gamma_dist;
15 typedef boost::uniform_01<engine_type> uniform01;
16 typedef boost::variate_generator<engine_type&, gamma_dist> gamma_generator;
20 static void init() { seedEngine = new engine_type(time(NULL)); }
21 static void init(seedType seed) { seedEngine = new engine_type(seed); }
23 static void finish() { if (seedEngine != NULL) delete seedEngine; }
25 static engine_type *new_engine() {
27 static std::set<seedType> seedSet; // empty set of seeds
28 std::set<seedType>::iterator iter;
31 seed = (*seedEngine)();
32 iter = seedSet.find(seed);
33 } while (iter != seedSet.end());
36 return new engine_type(seed);
40 static engine_type *seedEngine;
43 engine_type* engineFactory::seedEngine = NULL;
45 // arr should be cumulative!
47 // random number should be in [0, arr[len - 1])
48 // If by chance arr[len - 1] == 0.0, one possibility is to sample uniformly from 0...len-1
49 int sample(uniform01& rg, std::vector<double>& arr, int len) {
51 double prb = rg() * arr[len - 1];
56 if (arr[mid] <= prb) l = mid + 1;
60 if (l >= len) { printf("%d %lf %lf\n", len, arr[len - 1], prb); }