minimalize_pairs_ZZ()

void gbA::minimalize_pairs_ZZ ( spairs & new_set )

private

Definition at line 856 of file gb-default.cpp.

{
  // Prune down the set of spairs to a 'minimal' set.  For each one, we
  // need to add in a "gcd" combination spair as well.
 
  VECTOR(mpz_srcptr) coeffs;
  VECTOR(mpz_srcptr) coeffs2;
  VECTOR(exponents_t) exps;
  VECTOR(int) comps;
  VECTOR(int) positions;
 
  coeffs.reserve(gb.size());
  coeffs2.reserve(gb.size());
  exps.reserve(gb.size());
  comps.reserve(gb.size());
 
  for (VECTOR(spair *)::iterator i = new_set.begin(); i != new_set.end(); i++)
    {
      spair *a = *i;
      exps.push_back(a->lcm);
      comps.push_back(1); /* This is not needed here, as all of these
                             have the same component */
      /* Now get the coefficient */
      /* This is the lcm divided by the lead coeff, but it depends on the kind
       * of spair */
      if (a->type == SPAIR::SPAIR_SKEW)
        {
          coeffs.push_back(globalZZ->one().get_mpz());
          coeffs2.push_back(nullptr);  // will never be referred to below
        }
      else
        {
          /* */
          gbvector *f1 = gb[a->x.pair.i]->g.f;
          gbvector *f2 = gb[a->x.pair.j]->g.f;
          ring_elem u, v;
          globalZZ->syzygy(f1->coeff, f2->coeff, u, v);
          coeffs.push_back(u.get_mpz());
          coeffs2.push_back(v.get_mpz());
 
          if (mpz_cmpabs_ui(u.get_mpz(), 1) && mpz_cmpabs_ui(v.get_mpz(), 1))
            {
              spair *p2 = spair_make_gcd_ZZ(a->x.pair.i, a->x.pair.j);
              if (M2_gbTrace >= 4)
                {
                  buffer o;
                  o << "  creating ";
                  spair_text_out(o, p2);
                  emit_line(o.str());
                }
              spair_set_insert(p2);
            }
        }
    }
 
  if (_strategy == 0)
    MonomialTableZZ::find_weak_generators(
        _nvars, coeffs, exps, comps, positions);
  else
    MonomialTableZZ::find_weak_generators(
        _nvars, coeffs, exps, comps, positions, true);
 
  for (VECTOR(int)::iterator i = positions.begin(); i != positions.end(); i++)
    {
      // Insert this spair, and also the corresponding gcd one.
      spair *p = new_set[*i];
      if (M2_gbTrace >= 4)
        {
          buffer o;
          o << "  creating ";
          spair_text_out(o, p);
          emit_line(o.str());
        }
      spair_set_insert(p);
#if 0
      mpz_ptr u = coeffs[*i];
      mpz_ptr v = coeffs2[*i];
      if (p->type != SPAIR::SPAIR_SKEW && mpz_cmpabs_ui(u,1) && mpz_cmpabs_ui(v,1))
        {
          spair *p2 = spair_make_gcd_ZZ(p->x.pair.i, p->x.pair.j);
          if (M2_gbTrace >= 4)
            {
              buffer o;
              spair_text_out(o, p2);
              emit_line(o.str());
            }
          spair_set_insert(p2);
        }
#endif
    }
}

References _nvars, _strategy, gbvector::coeff, emit_line(), MonomialTableZZ::find_weak_generators(), gb(), ring_elem::get_mpz(), globalZZ, gbA::spair::lcm, M2_gbTrace, p, gbA::spair::pair, spair_make_gcd_ZZ(), spair_set_insert(), SPAIR_SKEW, spair_text_out(), buffer::str(), gbA::spair::type, VECTOR, and gbA::spair::x.

Referenced by minimalize_pairs().