coeff_of()

int hilb_comp::coeff_of ( const RingElement * h, int deg )

static

Definition at line 704 of file hilb.cpp.

{
  // This is a bit of a kludge of a routine.  The idea is to loop through
  // all the terms of the polynomial h, expand out the exponent, and to add
  // up the small integer values of the coefficients of those that have
  // exp[0]=deg.
  const PolynomialRing *P = h->get_ring()->cast_to_PolynomialRing();
 
  exponents_t exp = newarray_atomic(int, P->n_vars());
  int result = 0;
  for (Nterm& f : h->get_value())
    {
      P->getMonoid()->to_expvector(f.monom, exp);
      if (exp[0] < deg)
        {
          ERROR("incorrect Hilbert function given");
          fprintf(
              stderr,
              "internal error: incorrect Hilbert function given, aborting\n");
          fprintf(
              stderr,
              "exp[0]: %d   deg: %d\n", exp[0], deg);    
          abort();
        }
      else if (exp[0] == deg)
        {
          std::pair<bool, long> res =
              P->getCoefficientRing()->coerceToLongInteger(f.coeff);
          assert(res.first &&
                 std::abs(res.second) < std::numeric_limits<int>::max());
          int n = static_cast<int>(res.second);
          result += n;
        }
    }
  freemem(exp);
  return result;
}

References Ring::cast_to_PolynomialRing(), Ring::coerceToLongInteger(), ERROR, freemem(), RingElement::get_ring(), RingElement::get_value(), PolynomialRing::getCoefficientRing(), PolynomialRing::getMonoid(), PolynomialRing::n_vars(), newarray_atomic, result(), and Monoid::to_expvector().

Referenced by gb2_comp::calc_gb(), gbA::do_computation(), HilbertController::setDegree(), and GB_comp::start_computation().