Algorithm::CheckDigits::M16_001(3)

NAME
CheckDigits::M16_001 - compute check digits for ISAN

SYNOPSIS
  use Algorithm::CheckDigits;

  $isan = CheckDigits('isan');

  if ($isan->is_valid('123A567B8912E01A')) {
        # do something
  }

  $cn = $isan->complete('123A567B8912E01');
  # $cn = '123A567B8912E01A'

  $cd = $isan->checkdigit('123A567B8912E01A');
  # $cd = '4'

  $bn = $isan->basenumber('123A567B8912E01A');
  # $bn = '123A567B8912E01'

DESCRIPTION

  ALGORITHM

1.  "a(1) = 16"

    "b(i) = a(i) % 17 +d(i)", where d(i) is the decimal value of the hexdigit at position i.

    "c(i) = b(i) % 16"

    "a(i) = c(i-1) * 2", for i greater than 1

2.  Beginning left for each i = 1..16, "a", "b", "c" are computed.

3.  The check digit is the value for d(16) where c(16) equals 1.

4.  The check digit is appended as hexadecimal value to the number.

  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, "<mamawe@cpan.org>"

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