Measuring distance between two Lat/Lng points

Question

I am having issues trying to return the closest location to the user via an SQL statement. To test I am using the exact same coordinates, here is what I have: SQL: ``` SELECT `companies`.`customerName` , (3959 * ACOS( COS( RADIANS(37.367485) * COS(RADIANS(`locations`.`gps_lat`)) * COS( RADIANS(`locations`.`gps_lng`) - RADIANS(-77.399994) + SIN(RADIANS(37.367485)) * SIN(RADIANS(`locations`.`gps_lat`)) ) ) ) ) AS `distance` FROM `locations` JOIN `companies` ON `locations`.`co_id` HAVING `distance` > 25 ORDER BY distance LIMIT 0 , 10 ``` Results: ``` | customerName | distance | | SOME COMPANY | 1914.41747964854 | ``` `locations` table values: ``` gps_lat | gps_lng 37.367485 | -77.399994 ``` I used the example from Google, I checked the formula a couple times and I can't seem to come up with where I went wrong. Any help is appreciated. EDIT: Since there seems to be some confusion on me knowing what I am doing: The `>` was substituted to yield a result, `1914` is obviously greater then `25…

Accepted Answer

I think I have solved this issue by changing from Googles example to the formula provided by "Adventures of an adopted yooper". Using his/her version of the Haversine Formula. Note: The Google example above is using Haversine as well.

SQL:

```
SELECT  `companies`.`customerName` , 
(2 * (3959 * ATAN2(
          SQRT(
            POWER(SIN((RADIANS(37.367485 - `locations`.`gps_lat` ) ) / 2 ), 2 ) +
            COS(RADIANS(`locations`.`gps_lat`)) *
            COS(RADIANS(37.367485 )) *
            POWER(SIN((RADIANS(-77.399994 - `locations`.`gps_lng` ) ) / 2 ), 2 )
          ),
          SQRT(1-(
            POWER(SIN((RADIANS(37.367485 - `locations`.`gps_lat` ) ) / 2 ), 2 ) +
            COS(RADIANS(`locations`.`gps_lat`)) *
            COS(RADIANS(37.367485)) *
            POWER(SIN((RADIANS(-77.399994 - `locations`.`gps_lng` ) ) / 2 ), 2 )
          ))
        )
      ))
AS 'distance'
FROM  `locations` 
JOIN  `companies` ON  `locations`.`co_id` 
HAVING  distance < 25
ORDER BY distance
LIMIT 0 , 10
```

For those curious on my application, Final PHP:

GET Value: `?lat=37.367485&lng=-77.399994`

```
$earth_radius_miles = 3959; // Earth radius in miles
$earth_radius_kilometers = 6371; // Earth radius in kilometers
$result_radius = 10000; // Maximum distance in either miles or kilometers

$get_lat = $_GET["lat"];
$get_lng = $_GET["lng"];

$dbSelect = mysql_query("SELECT  `companies`.`customerName`,
(2 * (".$earth_radius_miles." * ATAN2(
          SQRT(
            POWER(SIN((RADIANS(".$get_lat." - `locations`.`gps_lat` ) ) / 2 ), 2 ) +
            COS(RADIANS(`locations`.`gps_lat`)) *
            COS(RADIANS(".$get_lat.")) *
            POWER(SIN((RADIANS(".$get_lng." - `locations`.`gps_lng` ) ) / 2 ), 2 )
          ),
          SQRT(1-(
            POWER(SIN((RADIANS(".$get_lat." - `locations`.`gps_lat` ) ) / 2 ), 2 ) +
            COS(RADIANS(`locations`.`gps_lat`)) *
            COS(RADIANS(".$get_lat.")) *
            POWER(SIN((RADIANS(".$get_lng." - `locations`.`gps_lng` ) ) / 2 ), 2 )
          ))
        )
      ))
AS 'distance'
FROM  `locations` 
JOIN  `companies` ON  `locations`.`co_id` 
HAVING  distance < ".$result_radius."
ORDER BY distance
LIMIT 0 , 10") 
or die(mysql_error());
```

Results:

```
[{"customerName":"SOME COMPANY","distance":"0"}]
```

I have tested these results with other coordinates and seems to be working perfectly. Haven't tested anything with great distance between the two points but my application doesn't require me to do so.

Measuring distance between two Lat/Lng points

Solution

Problem