NAME

       CheckDigits::MXX_006 - compute check digits with Verhoeff scheme

SYNOPSIS

         use Algorithm::CheckDigits;

         $verhoeff = CheckDigits('verhoeff');

         if ($verhoeff->is_valid('14567894')) {
               # do something
         }

         $cn = $verhoeff->complete('1456789');
         # $cn = '14567894'

         $cd = $verhoeff->checkdigit('14567894');
         # $cd = '4'

         $bn = $verhoeff->basenumber('14567894');
         # $bn = '1456789'

DESCRIPTION

   ALGORITHM
       1.  Right to left 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.

       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

       Jonathan Peters wrote Algorithm::Verhoeff from which I took the routine to compute the
       checkdigits.

SEE ALSO

       perl, CheckDigits, <http://www.cs.utsa.edu/~wagner/laws/verhoeff.html>,
       <http://www.cs.nmsu.edu/~cssem/Dickcheckdoc.pdf>