reducedgb.cpp

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#include "reducedgb.hpp"
 
#include "matrix-con.hpp"
#include "polyring.hpp"
#include "matrix.hpp"
 
#include "reducedgb-field.hpp"
#include "reducedgb-field-local.hpp"
#include "reducedgb-ZZ.hpp"
 
ReducedGB *ReducedGB::create(
    const PolynomialRing *originalR0,
    const FreeModule *F0,
    const FreeModule *Fsyz0,
    const GBWeight *wt0)  // better be 0 or set with same F0
{
  // Depending on whether the ring is over a field, or over ZZ, or
  // has local variables, we create a different class.
 
  bool over_ZZ = originalR0->coefficient_type() == Ring::COEFF_ZZ;
  bool is_local = originalR0->getMonoid()->numNonTermOrderVariables() > 0;
  GBRing *R = originalR0->get_gb_ring();
 
  if (over_ZZ)
    return new ReducedGB_ZZ(R, originalR0, F0, Fsyz0);
  else
    {
      if (is_local)
        return new ReducedGB_Field_Local(R, originalR0, F0, Fsyz0, wt0);
      else
        return new ReducedGB_Field(R, originalR0, F0, Fsyz0);
    }
}
 
ReducedGB::ReducedGB(GBRing *R0,
                     const PolynomialRing *originalR0,
                     const FreeModule *F0,
                     const FreeModule *Fsyz0)
    : R(R0), originalR(originalR0), F(F0), Fsyz(Fsyz0)
{
  set_status(COMP_DONE);
}
 
ReducedGB::~ReducedGB()
{
  for (int i = 0; i < polys.size(); i++)
    {
      R->gbvector_remove(polys[i].f);
      R->gbvector_remove(polys[i].fsyz);
    }
}
 
const Matrix /* or null */ *ReducedGB::get_gb()
{
  MatrixConstructor mat(F, 0);
  for (VECTOR(POLY)::const_iterator i = polys.begin(); i != polys.end(); i++)
    {
      vec v = originalR->translate_gbvector_to_vec(F, (*i).f);
      mat.append(v);
    }
  return mat.to_matrix();
}
 
const Matrix /* or null */ *ReducedGB::get_mingens()
{
#ifdef DEVELOPMENT
#warning "mingens?"
#endif
  return nullptr;
}
 
const Matrix /* or null */ *ReducedGB::get_syzygies()
{
#ifdef DEVELOPMENT
#warning "syzygies?"
#endif
  return nullptr;
}
 
const Matrix /* or null */ *ReducedGB::get_change()
{
  MatrixConstructor mat(Fsyz, 0);
  for (VECTOR(POLY)::const_iterator i = polys.begin(); i != polys.end(); i++)
    {
      vec v = originalR->translate_gbvector_to_vec(Fsyz, (*i).fsyz);
      mat.append(v);
    }
  return mat.to_matrix();
}
 
const Matrix /* or null */ *ReducedGB::get_initial(int nparts)
{
  MatrixConstructor mat(F, 0);
  for (VECTOR(POLY)::const_iterator i = polys.begin(); i != polys.end(); i++)
    {
      gbvector *f = R->gbvector_lead_term(nparts, F, (*i).f);
      mat.append(originalR->translate_gbvector_to_vec(F, f));
      R->gbvector_remove(f);
    }
  return mat.to_matrix();
}
 
const Matrix /* or null */ *ReducedGB::get_parallel_lead_terms(M2_arrayint w)
{
  MatrixConstructor mat(F, 0);
  for (int i = 0; i < polys.size(); i++)
    {
      gbvector *f =
          R->gbvector_parallel_lead_terms(w, F, polys[i].f, polys[i].f);
      mat.append(originalR->translate_gbvector_to_vec(F, f));
      R->gbvector_remove(f);
    }
  return mat.to_matrix();
}
 
void ReducedGB::text_out(buffer &o) const
{
  for (unsigned int i = 0; i < polys.size(); i++)
    {
      o << i << '\t';
      R->gbvector_text_out(o, F, polys[i].f);
      o << newline;
    }
}
 
const Matrix /* or null */ *ReducedGB::matrix_remainder(const Matrix *m)
{
  if (m->get_ring() != originalR)
    {
      ERROR("expected matrix over the same ring");
      return nullptr;
    }
 
  if (m->n_rows() != F->rank())
    {
      ERROR("expected matrices to have same number of rows");
      return nullptr;
    }
 
  MatrixConstructor red(m->rows(), m->cols(), m->degree_shift());
  for (int i = 0; i < m->n_cols(); i++)
    {
      ring_elem denom;
      gbvector *g = originalR->translate_gbvector_from_vec(F, (*m)[i], denom);
 
      remainder(g, true, denom);
 
      vec fv = originalR->translate_gbvector_to_vec_denom(F, g, denom);
      red.set_column(i, fv);
      R->gbvector_remove(g);
    }
  return red.to_matrix();
}
 
M2_bool ReducedGB::matrix_lift(const Matrix *m,
                               const Matrix /* or null */ **result_remainder,
                               const Matrix /* or null */ **result_quotient)
{
  if (m->get_ring() != originalR)
    {
      ERROR("expected matrix over the same ring");
      *result_remainder = nullptr;
      *result_quotient = nullptr;
      return false;
    }
  if (m->n_rows() != F->rank())
    {
      ERROR("expected matrices to have same number of rows");
      *result_remainder = nullptr;
      *result_quotient = nullptr;
      return false;
    }
 
  MatrixConstructor mat_remainder(m->rows(), m->cols(), m->degree_shift());
  MatrixConstructor mat_quotient(Fsyz, m->cols(), nullptr);
 
#ifdef DEVELOPMENT
#warning "K should be the denominator ring?"
#endif
  const Ring *K = R->get_flattened_coefficients();
  bool all_zeroes = true;
  for (int i = 0; i < m->n_cols(); i++)
    {
      ring_elem denom;
      POLY g;
      g.f = originalR->translate_gbvector_from_vec(F, (*m)[i], denom);
      g.fsyz = R->gbvector_zero();
 
      remainder(g, true, denom);
      if (g.f != nullptr) all_zeroes = false;
 
      vec fv = originalR->translate_gbvector_to_vec_denom(F, g.f, denom);
      K->negate_to(denom);
      vec fsyzv =
          originalR->translate_gbvector_to_vec_denom(Fsyz, g.fsyz, denom);
      mat_remainder.set_column(i, fv);
      mat_quotient.set_column(i, fsyzv);
 
      R->gbvector_remove(g.f);
      R->gbvector_remove(g.fsyz);
    }
  *result_remainder = mat_remainder.to_matrix();
  *result_quotient = mat_quotient.to_matrix();
  return all_zeroes;
}
 
int ReducedGB::contains(const Matrix *m)
{
  // Reduce each column of m one by one.
  if (m->get_ring() != originalR)
    {
      ERROR("expected matrix over the same ring");
      return -2;
    }
 
  for (int i = 0; i < m->n_cols(); i++)
    {
      ring_elem denom;
      gbvector *g = originalR->translate_gbvector_from_vec(F, (*m)[i], denom);
 
      remainder(g, false, denom);
 
      if (g != nullptr)
        {
          R->gbvector_remove(g);
          return i;
        }
    }
  return -1;
}
 
// Local Variables:
// compile-command: "make -C $M2BUILDDIR/Macaulay2/e "
// indent-tabs-mode: nil
// End: