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Text::Soundex(3pm)		 Perl Programmers Reference Guide	       Text::Soundex(3pm)

       Text::Soundex - Implementation of the Soundex Algorithm as Described by Knuth

	 use Text::Soundex;

	 $code = soundex $string;	     # get soundex code for a string
	 @codes = soundex @list;	     # get list of codes for list of strings

	 # set value to be returned for strings without soundex code

	 $soundex_nocode = 'Z000';

       This module implements the soundex algorithm as described by Donald Knuth in Volume 3 of
       The Art of Computer Programming.  The algorithm is intended to hash words (in particular
       surnames) into a small space using a simple model which approximates the sound of the word
       when spoken by an English speaker.  Each word is reduced to a four character string, the
       first character being an upper case letter and the remaining three being digits.

       If there is no soundex code representation for a string then the value of $soundex_nocode
       is returned.  This is initially set to "undef", but many people seem to prefer an unlikely
       value like "Z000" (how unlikely this is depends on the data set being dealt with.)  Any
       value can be assigned to $soundex_nocode.

       In scalar context "soundex" returns the soundex code of its first argument, and in list
       context a list is returned in which each element is the soundex code for the corresponding
       argument passed to "soundex" e.g.

	 @codes = soundex qw(Mike Stok);

       leaves @codes containing "('M200', 'S320')".

       Knuth's examples of various names and the soundex codes they map to are listed below:

	 Euler, Ellery -> E460
	 Gauss, Ghosh -> G200
	 Hilbert, Heilbronn -> H416
	 Knuth, Kant -> K530
	 Lloyd, Ladd -> L300
	 Lukasiewicz, Lissajous -> L222


	 $code = soundex 'Knuth';	       # $code contains 'K530'
	 @list = soundex qw(Lloyd Gauss);      # @list contains 'L300', 'G200'

       As the soundex algorithm was originally used a long time ago in the US it considers only
       the English alphabet and pronunciation.

       As it is mapping a large space (arbitrary length strings) onto a small space (single let-
       ter plus 3 digits) no inference can be made about the similarity of two strings which end
       up with the same soundex code.  For example, both "Hilbert" and "Heilbronn" end up with a
       soundex code of "H416".

       This code was implemented by Mike Stok ("stok@cybercom.net") from the description given by
       Knuth.  Ian Phillipps ("ian@pipex.net") and Rich Pinder ("rpinder@hsc.usc.edu") supplied
       ideas and spotted mistakes.

perl v5.8.0				    2002-06-01			       Text::Soundex(3pm)
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