Problem with simple graphics

[Lloyd Goldwasser]

I'm just getting started with Octave, with the current goal of running some 
existing code.  The graphics, even a simple plot command, doesn't seem to work. 
 A simple example is below.  I'm running Octave 3.4.0 on a Macbook Pro with Mac 
OS X 10.6.6, using the standard downloaded executable.

Any suggestions would be appreciated!

Thanks in advance,

Lloyd


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Last login: Mon Sep 19 18:36:43 on ttys000
exec '/Applications/Octave.app/Contents/Resources/bin/octave'
lloyd-goldwassers-macbook-pro-2:~ lloyd$ exec 
'/Applications/Octave.app/Contents/Resources/bin/octave'
GNU Octave, version 3.4.0
Copyright (C) 2011 John W. Eaton and others.
This is free software; see the source code for copying conditions.
There is ABSOLUTELY NO WARRANTY; not even for MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  For details, type `warranty'.

Octave was configured for "x86_64-apple-darwin10.7.3".

Additional information about Octave is available at http://www.octave.org.

Please contribute if you find this software useful.
For more information, visit http://www.octave.org/help-wanted.html

Read http://www.octave.org/bugs.html to learn how to submit bug reports.

For information about changes from previous versions, type `news'.

octave-3.4.0:1> clear
octave-3.4.0:2> a = 1:6
a =

   1   2   3   4   5   6

octave-3.4.0:3> plot (a)
error: popen2: popen2 (child): unable to start process -- No such file or 
directory
error: called from:
error:   
/Applications/Octave.app/Contents/Resources/share/octave/3.4.0/m/plot/__gnuplot_open_stream__.m
 at line 30, column 44
error:   
/Applications/Octave.app/Contents/Resources/share/octave/3.4.0/m/plot/__gnuplot_drawnow__.m
 at line 72, column 19
sh: gnuplot: command not found
error: `unset' undefined near line 4 column 1
warning: broken pipe -- some output may be lost