Function hasFirstAlgVar

factory/cf_ops.cc:679–692

check if poly f contains an algebraic variable a **/

/** check if poly f contains an algebraic variable a **/
bool hasFirstAlgVar( const CanonicalForm & f, Variable & a )
{
  if( f.inBaseDomain() ) // f has NO alg. variable
    return false;
  if( f.level()<0 ) // f has only alg. vars, so take the first one
  {
    a = f.mvar();
    return true;
  }
  for(CFIterator i=f; i.hasTerms(); i++)
    if( hasFirstAlgVar( i.coeff(), a ))
      return true; // 'a' is already set
  return false;
}

/** left shift the main variable of F by n
 *  @return if x is the main variable of F the result is F(x^n)