> restart;

> x:=r*cos(t):

> y:=r*sin(t):

> z:=x^2-y^2:

> b:=plot3d([x,y,z],r=0..1,t=0..2*Pi,scaling=constrained,grid=[10,100]):

> b;

> with(plottools):

Warning, the name changecoords has been redefined

> vrml(b,"c:/My Documents/mei/11.html/11-7.wrl",background_color=white):

>