The Euclidean Algorithm in XQuery

euclid.xqy

xquery version "3.1";

(: The Euclidean algorithm calculates the lowest common denominator of two integers :)

declare function local:euclid($num1 as xs:integer, $num2 as xs:integer) as xs:integer*
{
  if ($num1 > $num2) then local:euclid($num2, $num1 - $num2)
  else if ($num2 > $num1) then local:euclid($num1, $num2 - $num1)
  else $num1
};

local:euclid(13,8)

gcd.xqy

xquery version "3.1";

(: The Eculidean algorithm by division and remainder method -- much faster !:)

declare function local:gcd($num1 as xs:integer, $num2 as xs:integer) as xs:integer*
{
  if ($num1 > $num2 and $num1 mod $num2 != 0) then local:gcd($num2, $num1 mod $num2)
  else if ($num2 > $num1 and $num2 mod $num1 != 0) then local:gcd($num1, $num2 mod $num1)
  else $num2
};

local:gcd(13,8)