Editing Metaphone (section)

== Double Metaphone  {{anchor|Double Metaphone}} ==<!-- linked from redirect [[Double Metaphone]] -->
The Double Metaphone phonetic encoding algorithm is the second generation of this algorithm. Its implementation was described in the June 2000 issue of ''[[C/C++ Users Journal]]''.<ref>{{Cite journal|url=https://dl.acm.org/citation.cfm?id=349132|title = The double metaphone search algorithm|journal = C/C++ Users Journal|date = June 2000|volume = 18|issue = 6|pages = 38–43|last1 = Philips|first1 = Lawrence}}</ref> It makes a number of fundamental design improvements over the original Metaphone algorithm.

It is called "Double" because it can return both a primary and a secondary code for a string; this accounts for some ambiguous cases as well as for multiple variants of surnames with common ancestry. For example, encoding the name "Smith" yields a primary code of ''SM0'' and a secondary code of ''XMT'', while the name "Schmidt" yields a primary code of ''XMT'' and a secondary code of ''SMT''—both have ''XMT'' in common.

Double Metaphone tries to account for myriad irregularities in [[English language|English]] of [[Slavic languages|Slavic]], [[Germanic languages|Germanic]], [[Celtic languages|Celtic]], [[Greek language|Greek]], [[French language|French]], [[Italian language|Italian]], [[Spanish language|Spanish]], [[Chinese language|Chinese]], and other origins. Thus it uses a much more complex ruleset for coding than its predecessor; for example, it tests for approximately 100 different contexts of the use of the letter C alone.