\section{ISDIGIT Test for Digit Characters in a String}

\subsection{Usage}

The \verb|isdigit| functions returns a logical array that is 1 
for characters in the argument string that are digits, and 
is a logical 0 for characters in the argument that are not
digits.  The syntax for its use is
\begin{verbatim}
   x = isdigit(s)
\end{verbatim}
where \verb|s| is a \verb|string|.  
\subsection{Example}

A simple example of \verb|isdigit|:
\begin{verbatim}
--> isdigit('numb3r5')
ans = 
  <logical>  - size: [1 7]
 
Columns 1 to 7
 0  0  0  0  1  0  1  

\end{verbatim}
