New in Wolfram Mathematica 6: High-Impact Adaptive Visualization  previous | next 
Arbitrary Ribbon Plotting
Mathematica 6 allows arbitrary meshing, including transparent or removed sections of surfaces.
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Click for copyable input
Plot3D[(x^2 - y^2)/(x^2 + y^2)^2, {x, -1.5, 1.5}, {y, -1.5, 1.5}, 

 BoxRatios -> Automatic, PlotPoints -> 25, MeshFunctions -> {#3 &}, 

 MeshStyle -> Purple, MeshShading -> {None, Green, None, Yellow}]
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