Text::Soundex(3)					      Text::Soundex(3)

NAME    [Toc]    [Back]

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

SYNOPSIS    [Toc]    [Back]

       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    [Toc]    [Back]

     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 array 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    [Toc]    [Back]

     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:





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Text::Soundex(3)					      Text::Soundex(3)



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

LIMITATIONS    [Toc]    [Back]

     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    [Toc]    [Back]

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


									PPPPaaaaggggeeee 2222