Editing Tutorial (section)

===Visualizing plots===
In this example, we create a single trace full of noise and then send
it to sfgraph to produce a single VPLOT file, <tt>file.vpl</tt>.  As
you may have noticed, this only creates the file which is useful for
saving the plot, does not allow us to visualize the data.  To visualize
the data we need to use a '''pen''' , which tells your machine how
to actually draw the plot.  A typical Madagascar installation will
have multiple pens available for you to use.  By default, you should
use '''sfpen'''  which will pick the best pen available for you.
You can use '''sfpen'''  to visualize your plots in the following
manner:
<pre>
sfpen < file.vpl
</pre>
This will pop up a screen on your window with the plot shown.  Depending on which pen you are using you may be able to interact with the pen interface to control various parameters of the plot as shown by the buttons at the top of the screen.  Depending on the pen that you are using, there may be keyboard shortcuts to many of the buttons.  NOTE: '''oglpen'''  uses a mouse interface that can be accessed by right-clicking on the plot.