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

  function{ f_sphere(x, y, z, 2.3) }

  contained_by { sphere {<0,0,0>, -3.3 } }
  accuracy 0.003
  max_gradient 5

  texture{ pigment{ color rgb<1,1,0>}
           finish { specular 0.2 phong 1}}
  scale 0.5
  rotate<0,0,0>
  translate <-0.2, 1.3, 0>
} // end of isosurface -------------------------------------------------------