static inline float great_circle_distance_cosine(float lat1, float long1, float lat2, float long2) { float delta_long, temp1, temp2, delta_lat; delta_lat = lat2 - lat1; delta_long = long2 - long1; temp1 = sin(lat1) * sin(lat2); temp2 = cos(delta_lat); temp2 -= temp1; temp2 *= cos(delta_long); /* result is cos(lat1) cos(lat2) [ cos(lon1 - lon2) ] + sin(lat1) sin(lat2) */ return (temp1 + temp2); }