<?php
function getDistance($point1, $point2){

   $radius      = 3958;      // Earth's radius (miles)
   $pi          = 3.1415926;
   $deg_per_rad = 57.29578;  // Number of degrees/radian (for conversion)

   $distance = ($radius * $pi * sqrt(
               ($point1['lat'] - $point2['lat'])
               * ($point1['lat'] - $point2['lat'])
               + cos($point1['lat'] / $deg_per_rad)  // Convert these to
               * cos($point2['lat'] / $deg_per_rad)  // radians for cos()
               * ($point1['long'] - $point2['long'])
               * ($point1['long'] - $point2['long'])
       ) / 180);

   $distance = round($distance,1);
   return $distance;  // Returned using the units used for $radius.

}