How to calculate the distance between two UK postcodes using PHP

A PHP sample of triangulation which allows you to calculate the distance between postcodes. From http://www.sloomedia.com/php_postcode_script.php

A script and file to find distance between postcodes.
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<?php
function calc_postcode_seperation($pcodeA,$pcodeB)

{

// PCODE A

$result=mysql_query("SELECT * FROM postcodes WHERE Pcode='$pcodeA' LIMIT 1");

$row=mysql_fetch_array($result);

$gridn[0]=$row[Grid_N];

$gride[0]=$row[Grid_E];

// PCODE B
$result=mysql_query("SELECT * FROM postcodes WHERE Pcode='$pcodeB' LIMIT 1");

$row=mysql_fetch_array($result);

$gridn[1]=$row[Grid_N];

$gride[1]=$row[Grid_E];

// TAKE GRID REFS FROM EACH OTHER.

$distance_n=$gridn[0]-$gridn[1];

$distance_e=$gride[0]-$gride[1];

// CALCULATE THE DISTANCE BETWEEN THE TWO POINTS

$hypot=sqrt(($distance_n*$distance_n)+($distance_e*$distance_e));

$text.='Distance between '.$pcodeA.' and '.$pcodeB.' is: '.round($hypot/1000,2).'kms';

return $text;

}

echo calc_postcode_seperation('LE7','BD1');

?>

http://www.sloomedia.com/php_postcode_script.php

PHP  Postcode  Post  Code  distance  uk