\section{Built-in Module \module{soundex}}
\label{module-soundex}
\bimodindex{soundex}


The soundex algorithm takes an English word, and returns an
easily-computed hash of it; this hash is intended to be the same for
words that sound alike.  This module provides an interface to the
soundex algorithm.

Note that the soundex algorithm is quite simple-minded, and isn't
perfect by any measure.  Its main purpose is to help looking up names
in databases, when the name may be misspelled --- soundex hashes common
misspellings together.

\begin{funcdesc}{get_soundex}{string}
Return the soundex hash value for a word; it will always be a
6-character string.  \var{string} must contain the word to be hashed,
with no leading whitespace; the case of the word is ignored.  (Note
that the original algorithm produces a 4-character result.)
\end{funcdesc}

\begin{funcdesc}{sound_similar}{string1, string2}
Compare the word in \var{string1} with the word in \var{string2}; this
is equivalent to 
\code{get_soundex(\var{string1})} \code{==}
\code{get_soundex(\var{string2})}.
\end{funcdesc}


\begin{seealso}

\seetext{Donald E. Knuth, \emph{Sorting and Searching,} vol. 3 in
``The Art of Computer Programming.'' Addison-Wesley Publishing
Company:  Reading, MA: 1973. pp.\ 391-392.  Discusses the origin and
usefulness of the algorithm, as well as the algorithm itself.  Knuth
gives his sources as \emph{U.S. Patents 1261167} (1918) and
\emph{1435663} (1922), attributing the algorithm to Margaret K. Odell
and Robert C. Russel.  Additional references are provided.}

\end{seealso}