NAME

       CheckDigits::MXX_003 - compute check digits for DEM

SYNOPSIS

         use Algorithm::CheckDigits;

         $dem = CheckDigits('dem');

         if ($dem->is_valid('GD0645027K1')) {
               # do something
         }

         $cn = $dem->complete('GD0645027K');
         # $cn = 'GD0645027K1'

         $cd = $dem->checkdigit('GD0645027K1');
         # $cd = '1'

         $bn = $dem->basenumber('GD0645027K1');
         # $bn = 'GD0645027K'

DESCRIPTION

   ALGORITHM
       The algorithm is a variation of the Verhoeff scheme.

       0   All letters are changed to numbers.

       1   All digits are permutated according to a permutation table.

       2   The permutated digits are combined using a dieeder table. The first with the second,
           the result with the third, this result with the fourth and so on.

       3   The result of the last combination in the dieeder table is in such a way combined that
           the result is 0 (zero). The number used for this combination is the checksum.

       For details look at the source.

   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>

THANKS

SEE ALSO

       perl, CheckDigits, www.pruefziffernberechnung.de,