compare_isolated_roots_in_interval.h

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// Copyright (c) 2005  Stanford University (USA).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation; version 2.1 of the License.
// See the file LICENSE.LGPL distributed with CGAL.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the software.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $URL: svn+ssh://scm.gforge.inria.fr/svn/cgal/branches/CGAL-3.3-branch/Kinetic_data_structures/include/CGAL/Polynomial/internal/Rational/Compare_isolated_roots_in_interval.h $
// $Id: Compare_isolated_roots_in_interval.h 35772 2007-01-22 18:36:00Z drussel $
// 
//
// Author(s)     : Daniel Russel <[e-mail]>

#ifndef CGAL_COMPARE_ISOLATED_ROOTS_IN_INTERVAL_H
#define CGAL_COMPARE_ISOLATED_ROOTS_IN_INTERVAL_H

#include <CGAL/Polynomial/basic.h>

CGAL_POLYNOMIAL_BEGIN_INTERNAL_NAMESPACE

template<class Kernel, class M = CGAL::Integral_domain_without_division_tag>
class Compare_isolated_roots_in_interval
{
protected:
  typedef M                        Method_tag;
  typedef typename Kernel::FT  NT;

  typedef typename
  Kernel::Sign_Sturm_sequence Sign_Sturm_sequence;

public:
  Compare_isolated_roots_in_interval(const typename Kernel::Function& p,
				     const typename Kernel::Function& q,
				     Kernel k): kernel_(k),q(q), seq(kernel_.sign_Sturm_sequence_object(p, q)) {}

  Compare_isolated_roots_in_interval(){}

  typedef CGAL::Comparison_result  result_type;
  typedef NT                       argument_type;
  typedef NT                       first_argument_type;
  typedef NT                       second_argument_type;

  result_type operator()(const NT& a, const NT& b) const
  {
    int sgn = seq.sum_of_signs(a, b);

    if ( sgn == CGAL::ZERO ) { return CGAL::EQUAL; }

    int s_a = static_cast<int>(  kernel_.sign_at_object()(q, a) );

    if ( sgn == s_a ) { return CGAL::SMALLER; }
    return CGAL::LARGER;
  }

protected:
  Kernel kernel_;
  typename Kernel::Function          q;
  Sign_Sturm_sequence seq;
};

CGAL_POLYNOMIAL_END_INTERNAL_NAMESPACE
#endif                                            // CGAL_COMPARE_ISOLATED_ROOTS_IN_INTERVAL_H