Prediction: minor fixes.

modules/prediction/predictor/move_sequence/move_sequence_predictor.cc

@@ -555,9 +555,12 @@ double MoveSequencePredictor::CostFunction(
                               FLAGS_cost_function_alpha * time_to_end_state;
   if (FLAGS_use_bell_curve_for_cost_function) {
     double bell_curve_weight =
-        1 / std::sqrt(2 * M_PI * std::pow(FLAGS_cost_function_sigma, 2.0))
-        * std::exp(- std::pow(time_to_lane_edge - bell_curve_mu, 2.0) /
-                   (2 * std::pow(FLAGS_cost_function_sigma, 2.0)));
+        1 / std::sqrt(2 * M_PI * FLAGS_cost_function_sigma *
+                      FLAGS_cost_function_sigma)
+        * std::exp(
+          -(time_to_lane_edge - bell_curve_mu) *
+           (time_to_lane_edge - bell_curve_mu) /
+           (2 * FLAGS_cost_function_sigma * FLAGS_cost_function_sigma));
     cost_of_trajectory /= (bell_curve_weight + FLAGS_double_precision);
   }
   return cost_of_trajectory;