degree Phi
This is just a shortcut for (last multidegree Phi)/(degree image Phi).
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 rationalMap {f,g}; o2 : MultirationalMap (rational map from threefold in PP^3 x PP^2 x PP^4 to PP^2 x PP^4)
i3 : time degree Phi -- used 0.858511s (cpu); 0.650973s (thread); 0s (gc) o3 = 1