I get the proper graph with this function however I need to zoom on the intersection to show that the limit does not exist.

implicitplot3d((x^2-y^2)/(x^2+y^2), x = -.5 .. .5, y = -.5 .. .5, z = -2 .. 2, grid = [30, 30, 30])

When I enter this function, I only get a blank plot window. When I drag and drop it in the plot window I get an error.

implicitplot3d(z = xy^2/(x^2+y^4), x = -4 .. 4, y = -4 .. 4, z = -.5 .. .5, grid = [30, 30, 30])

Any help is greatly appreciated,

Jim Z