12-11

> restart;

> x:=r*cos(t):

> y:=r*sin(t):

> z:=x*y/(x^2+y^2):

> p:=plot3d([x,y,z],r=0..1,t=0..2*Pi,grid=[40,40],scaling=constrained):p;

> with(plottools):

> vrml(p,"c:/program files/maple 6/beauty/12-11.wrl",background_color=white);