RE: [PHP] lat lon function
| From: | Don Read | Date: | Tue, 08 Apr 2003 18:15:50 +0000 |
| Subject: | RE: [PHP] lat lon function | ||
| References: | 1 | Groups: | php.general |
| Request: | Send a blank email to php-general+get-142935@lists.php.net to get a copy of this message | ||
On 08-Apr-2003 Edward Peloke wrote:
>
> Don,
>
> How would I get distance? If my search is for a place with a lat of 30
> and
> long of 87 and I see a place with a lat of 31 and long of 88, how do you
> get
> the rough distance?
>
Forgot Pythagoras ?
c^2 = a^2 + b^2
mysql> set @a:=31-30;
Query OK, 0 rows affected (0.00 sec)
mysql> set @b:=88-87;
Query OK, 0 rows affected (0.00 sec)
mysql> set @d:=SQRT(POW(@a,2) + POW(@b,2));
Query OK, 0 rows affected (0.00 sec)
mysql> SELECT @d * 69;
+-----------------+
| @d * 69 |
+-----------------+
| 97.580735803744 |
+-----------------+
1 row in set (0.00 sec)
97.6 miles assuming a flat earth. To get a true distance, google 'spherical
trig' or 'law of cosines'.
Regards,
--
Don Read dread@texas.net
-- It's always darkest before the dawn. So if you are going to
steal the neighbor's newspaper, that's the time to do it.