Difference between revisions of "Package sagbi/SB.GetTruncSAGBI"

From ApCoCoAWiki
(added example)
m (edited example)
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Use QQ[x,y,z];
Use P ::= QQ[x,y,z];
S := SB.Subalgebra(CurrentRing,[x^2 -z^2,  x*y +z^2,  y^2 -2*z^2]);
S := SB.Subalgebra(P,[x^2 -z^2,  x*y +z^2,  y^2 -2*z^2]);
PrintLn SB.GetTruncSAGBI(S,3);
PrintLn SB.GetTruncSAGBI(S,3);
-- [y^2 -2*z^2,  x*y +z^2,  x^2 -z^2]</example>
-- [y^2 -2*z^2,  x*y +z^2,  x^2 -z^2]</example>

Revision as of 13:47, 28 October 2020

This article is about a function from ApCoCoA-2.


This function returns a truncated SAGBI basis of a given standard-graded subalgebra.


SB.GetTruncSAGBI(ref S: TAGGED(<quotes>$apcocoa/sagbi.Subalgebra</quotes>), d: INT): LIST of POLY


This function takes a subalgebra S generated by homogeneous polynomials as a reference, computes a d-truncated SAGBI basis, returns it and saves it into S if the function wasn't called previously. If the function was called previously on the same subalgebra with the same or a higher truncation degree d, then it just returns the truncated SAGBI basis of S.

  • @param S A subalgebra

  • @param d A positive integer

  • @return A d-truncated SAGBI basis of S


Use P ::= QQ[x,y,z];
S := SB.Subalgebra(P,[x^2 -z^2,  x*y +z^2,  y^2 -2*z^2]);
PrintLn SB.GetTruncSAGBI(S,3);
-- [y^2 -2*z^2,  x*y +z^2,  x^2 -z^2]

See also

HowTo:Call by Reference

HowTo:Term Orderings

Package sagbi/SB.GetTruncDeg

Package sagbi/SB.TruncSAGBI

Package sagbi/SB.GetID

Package sagbi/SB.GetRing

Package sagbi/SB.GetGens

Package sagbi/SB.GetCoeffRing

Package sagbi/SB.GetSAGBI

Package sagbi/SB.GetLTSA

Package sagbi/SB.GetInDeg

Package sagbi/SB.GetHS