Distance Between Two Latitude + LongitudePoints - PHP

by Bill Rawlinson —

I once had a project where the client wanted customers to be able to search for the nearest vendor to the customers zip code - this project was in PHP but the algorithim contained here can be translated to other languages pretty easily (Note, this returns the value in miles):

function computeDistance($lat1,$lon1,$lat2,$lon2){


 $lat1 =  deg2rad($lat1);

 $lon1 =  deg2rad($lon1);

 $lat2 =  deg2rad($lat2);

 $lon2 =  deg2rad($lon2);



// Find the deltas

      $delta_lat = $lat2 - $lat1;

      $delta_lon = $lon2 - $lon1;


// radius of earth in miles

 $r = 3963.1;


      // Find the Great Circle distance

      $distance = pow(sin($delta_lat/2.0),2) + cos($lat1) * cos($lat2) * pow(sin($delta_lon/2.0),2);

      $distance = $r * 2 * atan2(sqrt($distance),sqrt(1-$distance));


 return $distance;




}

Comments

Bill

That is probably a good suggestion however in my case I don’t know if is any more efficient. I’ll have to experiment. There are only about 10 global distributors and I don’t have a zipcode db to compute against. I have the coordinates of the warehouses and then a random zipcode. I then have to find the warehouse nearest the zipcode

Paul Hastings

and i’ll tell you the same thing i told kinky ben, use a bounding box instead.