I am trying to plot surfaces implicitly using implicitplot3d with their color dependent on the value of a function f(x,y,z). I have been unable to use the procedures listed in the help file for Plot3d Color Functions, but on the web I see examples of people using something like implicitplot3d(...., color=z). Did this used to work in an older version of Maple (I'm using 10)? John Starrett