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MultiprojectiveVarieties :: degree(MultirationalMap,Option)

degree(MultirationalMap,Option) -- degree of a multi-rational map using a probabilistic approach

Synopsis

Description

i1 : R = ZZ/33331[x_0..x_4];
i2 : Phi = (last graph multirationalMap rationalMap transpose jacobian(-x_2^3+2*x_1*x_2*x_3-x_0*x_3^2-x_1^2*x_4+x_0*x_2*x_4))||projectiveVariety ideal(random(2,R));

o2 : MultirationalMap (rational map from threefold in PP^4 x PP^4 to hypersurface in PP^4)
i3 : ? Phi

o3 = multi-rational map consisting of one single rational map
     source variety: threefold in PP^4 x PP^4 cut out by 13 hypersurfaces of
     target variety: hypersurface in PP^4 defined by a form of degree 2
     ------------------------------------------------------------------------
     multi-degrees (1,1)^3 (0,2)^1 (2,1)^8 (4,0)^1
i4 : time degree(Phi,Strategy=>"random point")
     -- used 2.081 seconds

o4 = 2
i5 : time degree(Phi,Strategy=>"0-th projective degree")
     -- used 0.490253 seconds

o5 = 2
i6 : time degree Phi
     -- used 0.388779 seconds

o6 = 2

Note, as in the example above, that calculation times may vary depending on the strategy used.

See also