Soundex

They are necessarily complex algorithms with many rules and exceptions, because English spelling and pronunciation is complicated by historical changes in pronunciation and words borrowed from many languages.

The Soundex code for a name consists of a letter followed by three numbers: the letter is the first letter of the name, and the numbers encode the remaining consonants. Vowels can affect the coding, but are never coded directly.

Metaphone was developed by Lawrence Philips as a response to deficiencies in the Soundex algorithm. Metaphone is available as a built-in operator in a number of systems, including later versions of PHP.

See also:

• Porter stemming algorithm[?]

External links:

• http://www.nara.gov/genealogy/soundex/soundex
• http://aspell.sourceforge.net/metaphone/
• Page for PHP implementation of Metaphone (http://www.zend.com/manual/function.metaphone.php)
• Freely available Soundex, Metaphone, and Double Metaphone implementation in Java at http://jakarta.apache.org/commons codec project