Damm algorithm: Difference between revisions

Revision as of 18:24, 8 February 2013

Revision as of 18:29, 8 February 2013

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== Strengths and weaknesses ==

The Damm algorithm is similar to the [[Verhoeff algorithm]]. It too will detect ''all'' occurrences of altering one single digit and ''all'' occurrences of transposing two adjacent digits. (These are the two most frequently appearing types of [[transcription error]]s.)<ref name=Kirtland2001 /> But the Damm algorithm has the benefit that it makes do without the dedicatedly constructed [[permutation]]s and its position specific [[Exponentiation#In_abstract_algebraIn abstract algebra|powers]] being inherent in the [[Verhoeff algorithm|Verhoeff scheme]]. Furthermore, a table of [[Inverse element|inverses]] can be dispensed with provided all diagonal entries of the operation table are zero.

The Damm algorithm does not suffer from exceeding the number of 10 possible values, resulting in the need for using a non-digit character (as the [[X]] in the [[ISBN#ISBN-10_check_digit_calculation10 check digit calculation|10-digit ISBN]] [[Check_digitCheck digit#ISBN_10ISBN 10|check digit]] scheme).

Prepending leading zeros does not affect the check digit.