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MultiprojectiveVarieties :: multidegree(ZZ,MultirationalMap)

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

Synopsis

Description

This is calculated by means of the inverse image of an appropriate random subvariety of the target.

i1 : Phi = last graph rationalMap PP_(ZZ/300007)^(1,4);

o1 : MultirationalMap (rational map from 4-dimensional subvariety of PP^4 x PP^5 to PP^5)
i2 : for i in {4,3,2,1,0} list time multidegree(i,Phi)
     -- used 0.00112158 seconds
     -- used 0.464277 seconds
     -- used 0.371631 seconds
     -- used 0.380039 seconds
     -- used 0.304554 seconds

o2 = {51, 28, 14, 6, 2}

o2 : List
i3 : time assert(oo == multidegree Phi)
     -- used 0.16703 seconds

References

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

See also