\section{rcond --- Condition Number}
\label{fn:rcond}
\index{rcond()}
\index{condition number}
\begin{rail}
RCond : 'rcond' '(' Matrix ')' ;
\end{rail}

\verb+rcond+ calculates a scalar that is an approximation to the
reciprocal of the condition number of the argument matrix.  An
approximation is used to reduce the computation required.


\paragraph{Example}
\index{example of rcond()}
\index{rcond()!example}
\begin{verbatim}
> a = rand(6,6)
 a =
 matrix columns 1 thru 6
    0.707      0.927      0.558      0.537      0.299      0.411  
    0.798      0.316      0.108      0.699      0.703      0.356  
    0.366     0.0293      0.207      0.589      0.485       0.65  
     0.67      0.188     0.0663      0.431       0.43      0.443  
    0.235      0.841      0.959       0.12      0.536      0.233  
    0.573        0.8      0.769      0.113      0.365      0.336  

> norm(a)*norm(inv(a))
      185
> rcond(a)
   0.0054
> 1/rcond(a)
      185
\end{verbatim}

See also: Page~\pageref{fn:det} \verb+det()+,
Page~\pageref{fn:inv} \verb+inv()+,
Page~\pageref{fn:lu} \verb+lu()+.

\newpage


