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kGonalNodalCurves :: getBackMatrix

getBackMatrix -- reconstructs a matrix from a list of entries and the position of those

Synopsis

Description

Reconstructs a matrix from a list of the type as computed by the function sparseKoszulMatrix.

i1 : (k,g,n)=(4,8,1000);
i2 : I=idealOfNodalCurve(k,g,n);

               ZZ
o2 : Ideal of ----[t , t , t , t , t , t , t , t ]
              1009  0   1   2   3   4   5   6   7
i3 : (charkk,rows,cols,entr)=sparseKoszulMatrix(I);
i4 : A1=getBackMatrix(charkk,rows,cols,entr);

              ZZ  120        ZZ  90
o4 : Matrix (----)    <--- (----)
             1009           1009
i5 : A2=criticalKoszulMap(I);

              ZZ  120        ZZ  90
o5 : Matrix (----)    <--- (----)
             1009           1009
i6 : rank A1==rank A2

o6 = true

See also

  • sparseKoszulMatrix -- computes list specifying the size of the critical Koszul map, the nonzero entries and the position of those

Ways to use getBackMatrix :

  • getBackMatrix(ZZ,ZZ,ZZ,List)