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Calculating pi from OpenMP

+double calculate_in_circle_random_count(void) {
+
+    static const unsigned total = 1000000000;
+    unsigned in_circle = 0;
+
+#pragma omp parallel reduction(+:in_circle)
+    {
+        // do per-thread initialization
+        rand_state seed = omp_srand();
+        int count = total / omp_get_num_threads();
+        int i;
+
+        // then do this thread's portion of the computation:
+        for (i = 0;  i < count;  ++i) {
+
+            double x = (double)omp_rand(&seed) / OMP_RAND_MAX;
+            double y = (double)omp_rand(&seed) / OMP_RAND_MAX;
+
+            double val = x * x + y * y;
+            in_circle +=  val < 1.0;
+        }
+    }
+    return 4.0 * in_circle / total;
+}
+
+int main(int argc, char const *argv[])
+{
+    int num_threads = 1;
+
+    if (argc > 1) 
+        num_threads = atoi(argv[1]);
+
+    omp_set_num_threads(num_threads);
+
+    float pi_approx = calculate_in_circle_random_count();
+
+    printf("Pi approximation: %.6f\n", pi_approx);
+
+    return 0;
+}