115 lines
3.4 KiB
C
115 lines
3.4 KiB
C
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// Copyright (c) 2006-2007 Max-Planck-Institute Saarbruecken (Germany).
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// All rights reserved.
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//
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// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public License as
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// published by the Free Software Foundation; either version 3 of the License,
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// or (at your option) any later version.
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//
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// Licensees holding a valid commercial license may use this file in
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// accordance with the commercial license agreement provided with the software.
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//
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// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
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// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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//
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// $URL$
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// $Id$
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// SPDX-License-Identifier: LGPL-3.0+
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//
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//
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// Author(s) : Michael Hemmer <hemmer@mpi-inf.mpg.de>
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//
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// =============================================================================
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#ifndef CGAL_CHINESE_REMAINDER_TRAITS_H
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#define CGAL_CHINESE_REMAINDER_TRAITS_H 1
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#include <CGAL/basic.h>
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#include <vector>
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#include <CGAL/extended_euclidean_algorithm.h>
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namespace CGAL{
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namespace internal{
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template <class T_, class TAG>
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class Chinese_remainder_traits_base{
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public:
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typedef T_ Type;
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typedef ::CGAL::Null_tag Scalar_type;
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typedef ::CGAL::Null_functor Chinese_remainder;
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};
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}
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template <class T> class Chinese_remainder_traits
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:public internal::Chinese_remainder_traits_base<T,
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typename Algebraic_structure_traits<T>::Algebraic_category>{};
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namespace internal {
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template <class NT>
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class Chinese_remainder_traits_base<NT,Euclidean_ring_tag>{
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public:
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typedef NT Type;
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typedef NT Scalar_type;
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struct Chinese_remainder{
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void operator() (
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const Scalar_type& m1, const Scalar_type& m2, const Scalar_type& m,
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const Scalar_type& s, const Scalar_type& CGAL_precondition_code(t),
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NT u1, NT u2,
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NT& u) const {
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#ifndef CGAL_NDEBUG
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NT tmp,s_,t_;
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tmp = CGAL::extended_euclidean_algorithm(m1,m2,s_,t_);
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CGAL_precondition(tmp == NT(1));
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CGAL_precondition(s_ == s);
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CGAL_precondition(t_ == t);
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#endif
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typedef Algebraic_structure_traits<NT> AST;
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typename AST::Mod mod;
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//typename AST::Unit_part unit_part;
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typename AST::Integral_division idiv;
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if(u1 < NT(0) ) u1 += m1;
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if(u2 < NT(0) ) u2 += m2;
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CGAL_precondition(0 < m1);
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CGAL_precondition(u1 < m1);
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CGAL_precondition(u1 >= NT(0));
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CGAL_precondition(0 < m2);
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CGAL_precondition(u2 < m2);
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CGAL_precondition(u2 >= NT(0));
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NT v = mod(s*(u2-u1),m2);
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u = m1*v + u1;
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// u is not unique yet!
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NT m_half = idiv(m-mod(m,NT(2)),NT(2));
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if (u > m_half) u -= m ;
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if (u <= -m_half) u += m ;
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}
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void operator() (
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const Scalar_type& m1, const Type& u1,
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const Scalar_type& m2, const Type& u2,
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Scalar_type& m, Type& u) const {
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Scalar_type s,t;
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CGAL::extended_euclidean_algorithm(m1,m2,s,t);
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m = m1 * m2;
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this->operator()(m1,m2,m,s,t,u1,u2,u);
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}
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};
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};
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} // namespace internal
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} // namespace CGAL
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#endif // CGAL_CHINESE_REMAINDER_TRAITS_H //
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