\section{WHERE Get Information on Program Stack}

\subsection{Usage}

Returns information on the current stack.  The usage is
\begin{verbatim}
   where
\end{verbatim}
The result is a kind of stack trace that indicates the state
of the current call stack, and where you are relative to the
stack.
\subsection{Example}

Suppose we have the following chain of functions.
\begin{verbatim}
    chain1.m
function chain1
  a = 32;
  b = a + 5;
  chain2(b)
\end{verbatim}
\begin{verbatim}
    chain2.m
function chain2(d)
  d = d + 5;
  chain3
\end{verbatim}
\begin{verbatim}
    chain3.m
function chain3
  g = 54;
  f = g + 1;
  keyboard
\end{verbatim}
The execution of the \verb|where| command shows the stack trace.
\begin{verbatim}
--> chain1
[chain3,4]--> where
In base(base) on line 0
In simkeys(built in) on line 0
In Eval(chain1) on line 2
In chain1(chain1) on line 4
In chain2(chain2) on line 4
In chain3(chain3) on line 4
In Eval(where) on line 2
In where(built in) on line 0
[chain3,4]
\end{verbatim}
