gistfile1.php

<?php
        /**
         *  Distance
         *
         *  @return distance betweeb two points in meters
         */
        public function distance($lat1,$long1,$lat2,$long2) 
        {
                $greatCircleRadius = 6372795;
         
                $rLat1 = M_PI*$lat1/180;
                $rLong1 = M_PI*$long1/180;
           
                $rLat2 = M_PI*$lat2/180;
                $rLong2 = M_PI*$long2/180;
           
                return abs($greatCircleRadius*atan(
                                  sqrt(
                                                pow(cos($rLat2)*sin($rLong2-$rLong1),2)
                                                +
                                                pow(cos($rLat1)*sin($rLat2)
                                                -
                                                sin($rLat1)*cos($rLat2)*cos(abs($rLong2-$rLong1)),2)
                                           )
                                  /
                                  (sin($rLat1)*sin($rLat2)+cos($rLat1)*cos($rLat2)*cos(abs($rLong2-$rLong1)))));
        }
?>