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multidegree(MultirationalMap) -- projective degrees of a multi-rational map

Function: multidegree
Usage:

multidegree Phi
Inputs:
- Phi, a multi-rational map
Outputs:
- a list, the list of projective degrees of Phi

Description

This calculates the multidegree of the graph and converts it to the list of projective degrees.

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 multidegree Phi
 -- used 0.981177s (cpu); 0.461985s (thread); 0s (gc)

o3 = {66, 46, 31, 20}

o3 : List

i4 : (degree source Phi,degree image Phi)

o4 = (66, 20)

o4 : Sequence

References

ArXiv preprint: Computations with rational maps between multi-projective varieties.

See also

multidegree(ZZ,MultirationalMap) -- i-th projective degree of a multi-rational map using a probabilistic approach
multidegree(RationalMap) -- projective degrees of a rational map
degree(MultirationalMap) -- degree of a multi-rational map
projectiveDegrees(RationalMap) -- projective degrees of a rational map

Ways to use this method:

multidegree(MultirationalMap) -- projective degrees of a multi-rational map

The source of this document is in MultiprojectiveVarieties.m2:3220:0.