vec_top_coefficient()

vec PolyRing::vec_top_coefficient ( const vec v, int & var, int & exp ) const

virtual

Implements PolynomialRing.

Definition at line 2374 of file poly.cpp.

{
  x = n_vars();
  e = 0;
  if (v == nullptr)
    {
      return nullptr;
    }
 
  exponents_t exp = newarray_atomic(int, n_vars());
  for (vec t = v; t != nullptr; t = t->next)
    for (Nterm& f : t->coeff)
      {
        M_->to_expvector(f.monom, exp);
        for (int i = 0; i < x; i++)
          {
            if (exp[i] > 0)
              {
                x = i;
                e = exp[i];
                break;
              }
          }
        if (x < n_vars() && exp[x] > e) e = exp[x];
      }
 
  // Now we have the variable, and its exponent.
  freemem(exp);
  if (x == n_vars()) return v;
  return vec_coefficient_of_var(v, x, e);
}

References Nterm::coeff, freemem(), PolynomialRing::M_, Nterm::monom, PolynomialRing::n_vars(), newarray_atomic, vec_coefficient_of_var(), and x.