CheckDigits::MBase_003(3) compute check digits for SICI (Serial Item

## 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-';

## 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 \$number consists solely of numbers and hyphens and the two digits in the middle are valid check digits according to the algorithm given above.

Returns false otherwise,

complete(\$number)
The check digit for \$number is computed and inserted into the middle of \$number.

Returns the complete number with check digit or '' if \$number does not consist solely of digits, hyphens and spaces.

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

Return '' otherwise.

checkdigit(\$number)
Returns the check digits of \$number if \$number has valid check digits.

Return '' otherwise.

None by default.

## AUTHOR

Mathias Weidner, <[email protected]>