\section{RREF Reduced Row Echelon Form of a Matrix}

\subsection{Usage}

Calculates the reduced row echelon form of a matrix using Gauss
Jordan elimination with partial pivoting.  The generic syntax
for \verb|rref| is 
\begin{verbatim}
   R = rref(A)
\end{verbatim}
A default tolerance of \verb|max(size(A))*eps*norm(A,inf)| is used to
detect negligible column elements.  The second form of \verb|rref| 
returns a vector \verb|k| as well as \verb|R|
\begin{verbatim}
  [R,k] = rref(A)
\end{verbatim}
where \verb|k| is a vector that correponds to the columns of \verb|A| 
used as pivot columns.  If you want to control the tolerance
used to identify negligible elements, you can use the form
\begin{verbatim}
  [R,k] = rref(A, tolerance)
\end{verbatim}
This implementation of \verb|rref| is based on the one from 
the matcompat lib for octave.  It is copyright Paul Kienzle,
and distributed under the GNU GPL. 
