Algorithm::CheckDigits::M11_013(3)

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 the rightmost digit is a valid check digit according to the algorithm given above.

    Returns false otherwise,

complete($number)
    The check digit for $number is computed and appended to the end of $number.

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

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, "<mamawe@cpan.org>"

SEE ALSO
perl, CheckDigits, www.pruefziffernberechnung.de,