Calculate distance between two points with MySQL

This function here is the right one. It returns pretty same results as the Google Maps distance, which leads me to believe that it's kind of correct.

	CREATE FUNCTION distance_between (from_lat DECIMAL(6, 3), from_lng DECIMAL(6, 3), to_lat DECIMAL(6, 3), to_lng DECIMAL(6, 3)) RETURNS DECIMAL(11, 3)
	RETURN 6371 * 2 * ATAN2(SQRT(POW(SIN(RADIANS(to_lat - from_lat)/2), 2) + POW(SIN(RADIANS(to_lng - from_lng)/2), 2) * COS(RADIANS(from_lat)) * COS(RADIANS(to_lat))), SQRT(1 - POW(SIN(RADIANS(to_lat - from_lat)/2), 2) + POW(SIN(RADIANS(to_lng - from_lng)/2), 2) * COS(RADIANS(from_lat)) * COS(RADIANS(to_lat))));

view raw distance_between.sql hosted with ❤ by GitHub

I've seen a lot of ready solutions online for the same input/output/platform combination (i.e. WGS84 degrees input/output on MySQL), but all of them used some other formula (at the end multiplying by 1.1515) that was producing some results that never worked for me.

On the other hand the following formula returns results identical with what Google Maps returns.

My function output

Cross check

Apparently there's some issue with the bearing and that's why the result is still not precisely accurate, but it's much closer than the other methods' outputs I've tried before.