Up number of iterations per thread

pi_threads.cpp

@@ -11,7 +11,7 @@ int main() {
 
     // n_threads * n_iterations_per_thread + 1 must fit in a uint32_t
     constexpr uint32_t n_threads = 4u;
-    constexpr uint32_t n_iterations_per_thread = 100000000u;
+    constexpr uint32_t n_iterations_per_thread = 1000000000u;
 
     std::array<std::thread, n_threads> threads;
     std::array<double, n_threads> thread_results;