I had the same problem until realizing that a parametric polar coordinate plot would do the trick. --Dan On 2013-04-26, at 11:41 PM, Bill Gosper wrote:
P.S. Out of curiosity, I just plotted the surface
z = (x^2 - y^2) / (x^2 + y^2)
which is of course just z = cos(2 theta),
and it gives a cute graph with a vertical interval as singular points at (x,y) = (0,0).
This is well-known to some people, but it wasn't to me.
You get essentially the identical graph for
z = 2xy / (x^2 + y^2) = sin(2 theta).
--Dan
I was trying to plot for a kid the corresponding verticality at 0^0, but I absolutely could not cajole Mma out to the edge. Macsyma does plot3d(x^y,x,0,1,y,0,1) with no fuss: gosper.org/x^y.bmp --rwg Well, you do have to make up a value for 0^0. How do you drag this surface out of Mma?