\section{ISALPHA Test for Alpha Characters in a String}

\subsection{Usage}

The \verb|isalpha| functions returns a logical array that is 1 
for characters in the argument string that are letters, and 
is a logical 0 for characters in the argument that are not
letters.  The syntax for its use is
\begin{verbatim}
   x = isalpha(s)
\end{verbatim}
where \verb|s| is a \verb|string|.  Note that this function is not
locale sensitive, and returns a logical 1 for letters in the
classic ASCII sense (a through z, and A through Z).
\subsection{Example}

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

\end{verbatim}
