NAME

       CheckDigits::M11_002 - compute check digits for PZN (DE)

SYNOPSIS

         use Algorithm::CheckDigits;

         $pzn = CheckDigits('pzn');

         if ($pzn->is_valid('4877800')) {
               # do something
         }

         $cn = $pzn->complete('487780');
         # $cn = '4877800'

         $cd = $pzn->checkdigit('4877800');
         # $cd = '0'

         $bn = $pzn->basenumber('4877800');
         # $bn = '487780'

DESCRIPTION

   ALGORITHM
       1.  From left to right beginning with the first position all digits are multiplied with
           2,3,4,...

       2.  The sum of all products is computed.

       3.  The checkdigit ist the sum of step 2 taken modulo 11.

       4.  If the checkdigit is '10' the whole number is not taken as a PZN.

   METHODS
       is_valid($number)
           Returns true only if $number consists solely of numbers and the last 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 concatenated to the end of $number.

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

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

           Return '' otherwise.

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

           Return '' otherwise.

   EXPORT
       None by default.

AUTHOR

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

SEE ALSO

       perl, CheckDigits, www.pruefziffernberechnung.de.