Location: PHPKode > scripts > Geocoder > geocoder/MathUtils.inc
```<?php

/*::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::*/
/*::                                                                         :*/
/*::  this routine calculates the distance between two points (given the     :*/
/*::  latitude/longitude of those points). it is being used to calculate     :*/
/*::  the distance between two zip codes or postal codes using our           :*/
/*::  zipcodeworld(tm) and postalcodeworld(tm) products.                     :*/
/*::                                                                         :*/
/*::  definitions:                                                           :*/
/*::    south latitudes are negative, east longitudes are positive           :*/
/*::                                                                         :*/
/*::  passed to function:                                                    :*/
/*::    lat1, lon1 = latitude and longitude of point 1 (in decimal degrees)  :*/
/*::    lat2, lon2 = latitude and longitude of point 2 (in decimal degrees)  :*/
/*::    unit = the unit you desire for results                               :*/
/*::           where: 'm' is statute miles                                   :*/
/*::                  'k' is kilometers (default)                            :*/
/*::                  'n' is nautical miles                                  :*/
/*::                                                                         :*/
/*::   see http://www.zipcodeworld.com/samples/distance.php.html             :*/
/*::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::*/

function distance(\$lat1, \$lon1, \$lat2, \$lon2, \$unit) {

\$theta = \$lon1 - \$lon2;
\$dist = acos(\$dist);
\$miles = \$dist * 60 * 1.1515;
\$unit = strtoupper(\$unit[0]);

if (\$unit == "K") {
return (\$miles * 1.609344);
}
else if (\$unit == "N") {
return (\$miles * 0.8684);
}
else {
return \$miles;
}
}

?>```