find_reduction_coeffs_ZZ()

bool GBRing::find_reduction_coeffs_ZZ	(	const FreeModule *	F,
		const gbvector *	f,
		const gbvector *	g,
		ring_elem &	v )

Definition at line 894 of file gbring.cpp.

{
  const ring_elem a = f->coeff;
  const ring_elem b = g->coeff;
  ring_elem rem;
 
  assert(globalZZ == K);
  rem = globalZZ->remainderAndQuotient(a, b, v);
  if (globalZZ->is_zero(v)) return false;
  v = globalZZ->negate(v);
 
  if (is_skew_commutative())
    {
      exponents_t EXP1 = ALLOCATE_EXPONENTS(exp_size);
      exponents_t EXP2 = ALLOCATE_EXPONENTS(exp_size);
      exponents_t EXP3 = ALLOCATE_EXPONENTS(exp_size);
      gbvector_get_lead_exponents(F, f, EXP1);  // Removes the Schreyer part
      gbvector_get_lead_exponents(F, g, EXP2);  // Removes the Schreyer part
      divide_exponents(EXP1, EXP2, EXP3);
      if (_skew.mult_sign(EXP3, EXP2) < 0) K->negate_to(v);
    }
 
  return globalZZ->is_zero(rem);
}

References _skew, ALLOCATE_EXPONENTS, gbvector::coeff, divide_exponents(), exp_size, gbvector_get_lead_exponents(), globalZZ, is_skew_commutative(), and K.

Referenced by gbvector_reduce_lead_term_ZZ().