Description
This function takes a polynomial ring in 4 variables over a field as the coordinate ring of P3 and creates a
CubicSurface in this ring. The equation of the cubic surface is computed from the blowup of 6 points in P2, listed in the key BlowUpPoints, along with a rational map P2 > P3 whose base loci is the 6 given points.
Synopsis

 Usage:
 X = quadricSurface(R)

Inputs:

Outputs:
i1 : cubicSurface(ZZ/32003[x,y,z,w])
2 2 2 2 2 2 2 2 3
o1 = ideal(2495x*y*z + 4036y z  5934y*z  2495x w  4289y w  1194y*z*w + 10682z w  8366x*w + 214y*w + 4197z*w  11134w )
o1 : CubicSurface
