What do you think of our new logo?????

By , March 21, 2012 11:15 PM
Open Moon Project

Open Moon Project

 

 

 

 

 

So what do you guys think of our new Logo??

Distance to Point, Great Cricle Distance, Cosine Theorem, Haversine formula

By , March 21, 2012 11:07 PM

Great Circle Distance Calculation

http://code.google.com/apis/maps/articles/phpsqlsearch.html

Finding locations nearby with MySQL

To find locations in our markers table that are within a certain radius distance of a given latitude/longitude, you can use a SELECT statement based on the Haversine formula. The Haversine formula is used generally for computing great-circle distances between two pairs of coordinates on a sphere. An in-depth mathemetical explanation is given by Wikipedia and a good discussion of the formula as it relates to programming is on Movable Type’s site.

Here’s the SQL statement that will find the closest 20 locations that are within a radius of 25 miles to the 37, -122 coordinate. It calculates the distance based on the latitude/longitude of that row and the target latitude/longitude, and then asks for only rows where the distance value is less than 25, orders the whole query by distance, and limits it to 20 results. To search by kilometers instead of miles, replace 3959 with 6371.

SELECT id, ( 3959 * acos( cos( radians(37) ) * cos( radians( lat ) ) * cos( radians( lng ) – radians(-122) ) + sin( radians(37) ) * sin( radians( lat ) ) ) ) AS distance FROM markers HAVING distance < 25 ORDER BY distance LIMIT 0 , 20;

 

SELECT ((ACOS(SIN($lat * PI() / 180) * SIN(`lat` * PI() / 180) + COS($lat * PI() / 180) * COS(`lat` * PI() / 180) * COS(($lon – `lon`) * PI() / 180)) * 180 / PI()) * 60 * 1.1515) AS distance FROM `members` HAVING distance<=’10′ ORDER BY distance ASC

 

Necessary reading for Great Circle Distance Calculations

http://code.google.com/apis/maps/articles/phpsqlsearch.html

http://www.movable-type.co.uk/scripts/latlong.html

http://zcentric.com/2010/03/11/calculate-distance-in-mysql-with-latitude-and-longitude/

http://www.scribd.com/doc/2569355/Geo-Distance-Search-with-MySQL

Thomas Challenger Thomas Challenger