CheckDigits::M11_013(3pm)				User Contributed Perl Documentation				 CheckDigits::M11_013(3pm)

NAME

       CheckDigits::M11_013 - compute check digits for VAT Registration Number (GR)

SYNOPSIS

	 use Algorithm::CheckDigits;

	 $ustid = CheckDigits('ustid_gr');

	 if ($ustid->is_valid('123456783')) {
	       # do something
	 }

	 $cn = $ustid->complete('12345678');
	 # $cn = '123456783'

	 $cd = $ustid->checkdigit('123456783');
	 # $cd = '3'

	 $bn = $ustid->basenumber('123456783');
	 # $bn = '12345678';

DESCRIPTION

   ALGORITHM
       1.  Beginning right with the digit before the checkdigit all digits are weighted with 2 ** position. I. e. the last digit is multiplied
	   with 2, the next with 4, then 8 and so on.

       2.  The weighted digits are added.

       3.  The sum from step 2 is taken modulo 11.

       4.  If the sum from step 3 is greater than 9, the check sum is 0 else it is the sum itself.

   METHODS
       is_valid($number)
	   Returns true only if $number consists solely of numbers and hyphens and the two digits in the middle are valid check digits according
	   to the algorithm given above.

	   Returns false otherwise,

       complete($number)
	   The check digit for $number is computed and inserted into the middle of $number.

	   Returns the complete number with check digit or '' if $number does not consist solely of digits, hyphens and spaces.

       basenumber($number)
	   Returns the basenumber of $number if $number has a valid check digit.

	   Return '' otherwise.

       checkdigit($number)
	   Returns the check digits of $number if $number has valid check digits.

	   Return '' otherwise.

   EXPORT
       None by default.

AUTHOR

       Mathias Weidner, <mathias@weidner.in-bad-schmiedeberg.de>

SEE ALSO

       perl, CheckDigits, www.pruefziffernberechnung.de,

perl v5.10.0							    2008-05-17						 CheckDigits::M11_013(3pm)