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

I'm a brand new user. 

Maple 12, Windows Vista, Integration Tutor.

When viewing the steps in the solution, Maple does it's own u-subs ("change of variable").  Is there any way to see what it is setting "u=?"?

It's very difficult to follow the steps when I can't tell what it's subbing out.

Also, within the same tutor, it doesn't seem to like to intigrate to infinity.  It tells me "...infinity should be a number."  ! ? ! ?

Thank you in advance.

Jim Z