NAME

CheckDigits::MBase_003 - compute check digits for SICI (Serial Item and Contribution Identifier)

SYNOPSIS

  use Algorithm::CheckDigits;

  $sici = CheckDigits('sici');

  if ($sici->is_valid('0784-8679(20040308)6:<138>2.0.TX;2-H')) {
	# do something
  }

  $cn = $sici->complete('0784-8679(20040308)6:<138>2.0.TX;2-');
  # $cn = '0784-8679(20040308)6:<138>2.0.TX;2-H'

  $cd = $sici->checkdigit('0784-8679(20040308)6:<138>2.0.TX;2-H');
  # $cd = 'H'

  $bn = $sici->basenumber('0784-8679(20040308)6:<138>2.0.TX;2-H');
  # $bn = '0784-8679(20040308)6:<138>2.0.TX;2-';
  

DESCRIPTION

ALGORITHM

0

In the string describing the number all letters (A-Z) are replaced with numbers 10-35 accordingly. All other non-numbers are replaced by 36.

1

Beginning right the numbers at all odd positions are added.

2

The sum from step 1 is multiplied by 3.

3

Beginning right the numbers at all even positions are added.

4

The sums from step 2 and 3 are added.

5

The sum from step 4 is taken modulo 37.

6

The checksum is 37 minus the sum from step 5 where numbers from 10 to 35 are represented by 'A' to 'Z' accordingly and 36 is represented by '#'.

METHODS

is_valid($number)

Returns true only if the last letter is a valid check letter according to the algorithm given above.

Returns false otherwise,

complete($number)

The check letter for $number is computed and appended the end of $number.

Returns the complete number with check letter or ''.

basenumber($number)

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

Return '' otherwise.

checkdigit($number)

Returns the check letter of $number if $number has valid check digits.

Return '' otherwise.

EXPORT

None by default.

AUTHOR

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

SEE ALSO

perl, CheckDigits, www.pruefziffernberechnung.de, http://sunsite.berkeley.edu/SICI/sici.pdf