calculate distance

Question

i am designing a recruitment database, and i need it to perform several tasks that all involve integrating a way of calculating distance:

1) calculate the distance t

Answer 1

The distance between 2 points could be calculated with the following formula :

6371*acos(cos(LatitudeA)*cos(LatitudeB)*cos(longitudeB-longitudeA)+sin(LatitudeA)*sin(latitudeB))

Of course it's a "crow flies" approximation in Km.

Wich can be translated to php by :

$longA     = 2.3458*(M_PI/180); // M_PI is a php constant
$latA     = 48.8608*(M_PI/180);
$longB     = 5.0356*(M_PI/180);
$latB     = 47.3225*(M_PI/180);

$subBA       = bcsub ($longB, $longA, 20);
$cosLatA     = cos($latA);
$cosLatB     = cos($latB);
$sinLatA     = sin($latA);
$sinLatB     = sin($latB);

$distance = 6371*acos($cosLatA*$cosLatB*cos($subBA)+$sinLatA*$sinLatB);
echo $distance ;

With that you could compute the distance between two points (people) and of course determine if a point is in a radius of an other.