rawFourierMotzkin()

const Matrix * rawFourierMotzkin

(

const Matrix *

C

)

Cone interface routines

Definition at line 23 of file cone.cpp.

{
  try
    {
      // TODO: generalize the input type, in particular to allow lineality space
      const Ring *R = C->get_ring();
      const size_t c = C->n_cols();  // rank of ambient lattice
      const size_t r = C->n_rows();  // number of cone inequalities
 
      auto ineqs = libnormaliz::Matrix<Integer>(r, c);
      for (size_t i = 0; i < r; i++)
        for (size_t j = 0; j < c; j++)
      // libnormaliz uses A*x >= 0, Macaulay2 uses A*x <= 0
          ineqs[i][j] = (-1) * static_cast<Integer>(C->elem(i, j).get_mpz());
 
      auto cone = libnormaliz::Cone<Integer>(libnormaliz::Type::inequalities, ineqs);
      auto rays = cone.getExtremeRays();
      size_t n = rays.size();  // number of extremal rays
 
      MatrixConstructor mat(R->make_FreeModule(n), c);
      for (size_t i = 0; i < n; i++)
        for (size_t j = 0; j < c; j++)
          {
            mpz_ptr z = newitem(__mpz_struct);
            mpz_init_set(z, rays[i][j].get_mpz_t());
            mpz_reallocate_limbs(z);
            mat.set_entry(i, j, ring_elem(z));
          }
 
      return mat.to_matrix();
  } catch (const exc::engine_error &e)
    {
      ERROR(e.what());
      return nullptr;
  }
}

References Matrix::elem(), ERROR, Matrix::get_ring(), Ring::make_FreeModule(), Matrix, mpz_reallocate_limbs(), Matrix::n_cols(), Matrix::n_rows(), newitem, MatrixConstructor::set_entry(), and MatrixConstructor::to_matrix().