CheckDigits::M16_001(3pm)				User Contributed Perl Documentation				 CheckDigits::M16_001(3pm)

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

SEE ALSO

       perl, CheckDigits, www.pruefziffernberechnung.de.

perl v5.10.0							    2008-05-17						 CheckDigits::M16_001(3pm)