This module allows to visualize a Fsignal on the screen.
\index{visualization!of a signal}

\medskip

The \verb+-x+ and \verb+-y+ options specify the position of the
window on the screen, and the the \verb+-X+ and \verb+-Y+ options 
rule the wiindow size. This module can be called with \verb+-n+
and \verb+-o+ options to store the display image instead of
visualizing the result on the screen.

\bigskip

Interactive commands:

\bigskip

{\bf Keyboard:}
\begin{tabular}{lll}
&  Q:  &Quit.\\
&  H:  &Help.\\
&  G:  &Grid mode (switch).\\
&  S:  &Scaling (zoom y axis).\\
&  U:  &Unzoom (x and y).\\
&  P:  &Point/Line/boxes representation (switch).\\
&  L/Left arrow:   &Go Left.\\
&  R/Right arrow:  &Go Right.\\
&  Up arrow:       &Go Up.\\
&  Down arrow:     &Go Down.\\
\end{tabular}

\bigskip

{\bf Mouse:}
\begin{tabular}{lll}
&  Left button:    & Select a region of interest. \\
&  Middle button:  & Restore the original display region.\\
&  Right button:   & Zoom on the selected x location.\\
&  Wheel button:   & Roll to Go Up or Down.
\end{tabular}


