internal_subtract_to()

void FractionField::internal_subtract_to	(	ring_elem &	f,
		ring_elem &	g ) const

Definition at line 436 of file frac.cpp.

{
  frac_elem *f = FRAC_VAL(a);
  frac_elem *g = FRAC_VAL(b);
  if (R_->is_equal(f->denom, g->denom))
    R_->subtract_to(f->numer, g->numer);
  else
    {
      R_->mult_to(f->numer, g->denom);
      ring_elem tmp = R_->mult(f->denom, g->numer);
      R_->subtract_to(f->numer, tmp);
      R_->mult_to(f->denom, g->denom);
      if (R_->is_zero(f->denom))
        {
          set_non_unit_frac(g->denom);
          return;
        }
    }
  simplify(f);
  remove(b);
  a = FRAC_RINGELEM(f);
}

References frac_elem::denom, FRAC_RINGELEM, FRAC_VAL, frac_elem::numer, R_, remove(), set_non_unit_frac(), and simplify().