232.sagews

# Graph for 16.2 #46
# ------------------

# We can graph the fence as a parametric surface in the variables t and s,
# where we use the variable t to run over the curve (i.e., the base of the fence)
# and the variable s to go from the bottom of the fence to the top.

var('t,s')
h(x,y) = 4 + 0.001*(x^2 - y^2)
fence = parametric_plot3d((10*cos(t),10*sin(t),s*h(10*cos(t),10*sin(t))),\
    (t,0,2*pi),(s,0,1),rgbcolor=(0.8,0.9,0.2))
funct = plot3d(h,(x,-15,15),(y,-15,15),opacity=0.5,color='yellow')
(funct + fence).show(aspect_ratio=[1,1,2])