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

NAME

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

SYNOPSIS

	 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';

DESCRIPTION

       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 spo-
       ken by an English speaker.  Each word is reduced to a four character string, the first character being an upper case letter and the remain-
       ing 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')".

EXAMPLES

       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

       so:

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

LIMITATIONS

       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 letter 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".

AUTHOR

       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)