This computation is performed by converting the multi-rational map to a standard rational map (using segre) and then applying the corresponding method for rational maps.
i1 : ZZ/300007[x_0..x_3], f = rationalMap {x_2^2-x_1*x_3, x_1*x_2-x_0*x_3, x_1^2-x_0*x_2}, g = rationalMap {x_1^2-x_0*x_2, x_0*x_3, x_1*x_3, x_2*x_3, x_3^2}; |
i2 : Phi = last graph multirationalMap {f,g} o2 = Phi o2 : MultirationalMap (rational map from threefold in PP^3 x PP^2 x PP^4 to PP^2 x PP^4) |
i3 : time projectiveDegrees Phi -- used 5.09782 seconds o3 = {66, 46, 31, 20} o3 : List |
i4 : (degree source Phi,degree image Phi) o4 = (66, 20) o4 : Sequence |