isosurface { //-------------------------------------------------------------

  function {  f_paraboloid(x,-y,z, -1)
           }
  contained_by { box { -2, 2 } }
  accuracy 0.002
  max_gradient 4

  texture{ pigment{ color rgb<0.5,1,0.1>}
           finish { phong 1}}
  scale 1
  rotate<0,30,0>
  translate <0,2.2,0> 
} // end of isosurface -------------------------------------------------------
