\section{ISEMPTY Test For Variable Empty}

\subsection{Usage}

The \verb|isempty| function returns a boolean that indicates
if the argument variable is empty or not.  The general
syntax for its use is
\begin{verbatim}
  y = isempty(x).
\end{verbatim}
\subsection{Examples}

Here are some examples of the \verb|isempty| function
\begin{verbatim}
--> a = []
a = 
  <double>  - size: [0 0]
  []
--> isempty(a)
ans = 
  <logical>  - size: [1 1]
 1  
--> b = 1:3
b = 
  <int32>  - size: [1 3]
 
Columns 1 to 3
 1  2  3  
--> isempty(b)
ans = 
  <logical>  - size: [1 1]
 0  

\end{verbatim}
Note that if the variable is not defined, \verb|isempty| 
does not return true.
\begin{verbatim}
--> clear x
--> isempty(x)
Error: Undefined function or variable x

\end{verbatim}
