contour_plots



L.S.,

Is it possible to create contourplots with Maxima 5.9.2 (and wxMaxima 0.6.4)

For example : the command 
                     contour_plot(x^2+y^2,[x,-4,4],[y,-4,4])
                     gives only an echo

Can you help me ?

Thanks in advance !

Jos? Simons