---find_point_value :: RealFunction Point
---find_point_value p = poly p
--- where
--- g0 = make_grid 1 trilinear
--- the_cubes = flatten (cubes g0)
--- good_cubes = filter ((flip contains_point) p) the_cubes
--- target_cube = head good_cubes
--- good_tets = filter ((flip contains_point) p) (tetrahedrons target_cube)
--- target_tetrahedron = head good_tets
--- poly = polynomial target_tetrahedron