to_M2_MutableMatrix() [1/2]

MutableMatrix * ResF4toM2Interface::to_M2_MutableMatrix ( SchreyerFrame & C, const Ring * K, int lev, int degree )

static

Definition at line 320 of file res-f4-m2-interface.cpp.

{
  // The ring K should be the coefficient ring of the poly ring of C,
  // OR: if the coefficient ring is QQ, then it can be RR, or a finite field.
 
  // Now we loop through the elements of degree 'degree' at level 'lev'
  auto& thislevel = C.level(lev);
  int n = 0;
  for (auto p = thislevel.begin(); p != thislevel.end(); ++p)
    {
      if (p->mDegree == degree) n++;
    }
 
  auto& prevlevel = C.level(lev - 1);
  int* newcomps = new int[prevlevel.size()];
  int nextcomp = 0;
  for (int i = 0; i < prevlevel.size(); i++)
    if (prevlevel[i].mDegree == degree)
      newcomps[i] = nextcomp++;
    else
      newcomps[i] = -1;
 
  // create the mutable matrix
  MutableMatrix* result = MutableMatrix::zero_matrix(K, nextcomp, n, true);
  // Now loop through the elements at thislevel,
  // and for each, loop through the terms of mSyzygy.
  // if the component x satisfies newcomps[x] >= 0, then place
  // this coeff into the mutable matrix.
  int col = 0;
 
  for (auto p = thislevel.begin(); p != thislevel.end(); ++p)
    {
      if (p->mDegree != degree) continue;
      auto& f = p->mSyzygy;
      auto end = ResPolynomialIterator(C.ring(), f, 1);
      auto i = ResPolynomialIterator(C.ring(), f);
      for (; i != end; ++i)
        {
          long comp = C.monoid().get_component(i.monomial());
          if (newcomps[comp] >= 0)
            {
              ring_elem a = C.ring().vectorArithmetic().ringElemFromElementArray(
                  f.coeffs, i.coefficient_index());
              result->set_entry(newcomps[comp], col, a);
            }
        }
      ++col;
    }
 
  delete[] newcomps;
  return result;
}

References end(), ResMonoidDense::get_component(), SchreyerFrame::level(), SchreyerFrame::monoid(), p, result(), SchreyerFrame::ring(), VectorArithmetic::ringElemFromElementArray(), ResPolyRing::vectorArithmetic(), and MutableMatrix::zero_matrix().