Singular

D.15.16.9 GITfanParallel

Usage:

GITfanParallel(OC, Q, Qgamma [, file1]); OC:list, Q:intmat, Qgamma:cone, file1:string

Purpose:

Returns the common refinement of the cones given in
the list OC which is supposed to contain the orbit cones intersected with Qgamma. The optional argument can be used to specify a name for a file which will contain the hashes of the GIT-cones. To obtain the whole GIT-fan Qgamma has to be take the cone generated by the columns of Q.

Return:

a list containing the bigint hashes of the GIT cones.

Note:

The proceduce uses parallel computation for the construction of the GIT-cones.

LIB "gitfan.lib";
setcores(4);
==> 4
ring R = 0,T(1..10),wp(1,1,1,1,1,1,1,1,1,1);
ideal J =
T(5)*T(10)-T(6)*T(9)+T(7)*T(8),
T(1)*T(9)-T(2)*T(7)+T(4)*T(5),
T(1)*T(8)-T(2)*T(6)+T(3)*T(5),
T(1)*T(10)-T(3)*T(7)+T(4)*T(6),
T(2)*T(10)-T(3)*T(9)+T(4)*T(8);
intmat Q[5][10] =
1, 1, 1, 1, 0, 0, 0, 0, 0, 0,
1, 0, 0, 0, 1, 1, 1, 0, 0, 0,
0, 1, 1, 0, 0, 0, -1, 1, 0, 0,
0, 1, 0, 1, 0, -1, 0, 0, 1, 0,
0, 0, 1, 1, -1, 0, 0, 0, 0, 1;
list AF= afaces(J);
print(size(AF));
==> 172
list OC = orbitCones(AF,Q);
cone Qgamma = coneViaPoints(transpose(Q));
list GIT = GITfanParallel(OC,Q,Qgamma);
size(GIT);
==> 76