add citation and remove pass by reference for native type

src/lib/pure_pursuit/PurePursuit.cpp

@@ -36,7 +36,7 @@
 
 float PurePursuit::calcDesiredHeading(const Vector2f &curr_wp_ned, const Vector2f &prev_wp_ned,
 				      const Vector2f &curr_pos_ned,
-				      const float &lookahead_distance)
+				      const float lookahead_distance)
 {
 	// Check input validity
 	if (!curr_wp_ned.isAllFinite() || !curr_pos_ned.isAllFinite() || lookahead_distance < FLT_EPSILON

src/lib/pure_pursuit/PurePursuit.hpp

@@ -40,6 +40,13 @@ using namespace matrix;
  *
  * Implementation of pure pursuit guidance logic.
  *
+ * Acknowledgements and References:
+ *
+ *    This implementation has been built for PX4 based on the idea from [1] (not including any code).
+ *
+ *    [1] Coulter, R. C. (1992). Implementation of the Pure Pursuit Path Tracking Algorithm
+ * 	  (Techreport CMU-RI-TR-92-01).
+ *
  * Pure pursuit is a path following algorithm that uses the intersection between the path and
  * a circle (the radius of which is referred to as lookahead distance) around the vehicle as
  * the target point for the vehicle.
@@ -80,5 +87,5 @@ class PurePursuit
 	 * @param lookahead_distance Radius of circle around vehicle [m].
 	 */
 	float calcDesiredHeading(const Vector2f &curr_wp_ned, const Vector2f &prev_wp_ned, const Vector2f &curr_pos_ned,
-				 const float &lookahead_distance);
+				 const float lookahead_distance);
 };