106 lines
3.0 KiB
C++
106 lines
3.0 KiB
C++
// Copyright (c) 2006-2007 Max-Planck-Institute Saarbruecken (Germany).
|
|
// All rights reserved.
|
|
//
|
|
// This file is part of CGAL (www.cgal.org)
|
|
//
|
|
// $URL: https://github.com/CGAL/cgal/blob/v5.1/Algebraic_foundations/include/CGAL/Chinese_remainder_traits.h $
|
|
// $Id: Chinese_remainder_traits.h 0779373 2020-03-26T13:31:46+01:00 Sébastien Loriot
|
|
// SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-Commercial
|
|
//
|
|
//
|
|
// Author(s) : Michael Hemmer <hemmer@mpi-inf.mpg.de>
|
|
//
|
|
// =============================================================================
|
|
|
|
|
|
#ifndef CGAL_CHINESE_REMAINDER_TRAITS_H
|
|
#define CGAL_CHINESE_REMAINDER_TRAITS_H 1
|
|
|
|
#include <CGAL/basic.h>
|
|
|
|
#include <vector>
|
|
|
|
#include <CGAL/extended_euclidean_algorithm.h>
|
|
|
|
namespace CGAL{
|
|
namespace internal{
|
|
|
|
template <class T_, class TAG>
|
|
class Chinese_remainder_traits_base{
|
|
public:
|
|
typedef T_ Type;
|
|
typedef ::CGAL::Null_tag Scalar_type;
|
|
typedef ::CGAL::Null_functor Chinese_remainder;
|
|
};
|
|
}
|
|
|
|
template <class T> class Chinese_remainder_traits
|
|
:public internal::Chinese_remainder_traits_base<T,
|
|
typename Algebraic_structure_traits<T>::Algebraic_category>{};
|
|
|
|
|
|
namespace internal {
|
|
template <class NT>
|
|
class Chinese_remainder_traits_base<NT,Euclidean_ring_tag>{
|
|
public:
|
|
typedef NT Type;
|
|
typedef NT Scalar_type;
|
|
|
|
struct Chinese_remainder{
|
|
void operator() (
|
|
const Scalar_type& m1, const Scalar_type& m2, const Scalar_type& m,
|
|
const Scalar_type& s, const Scalar_type& CGAL_precondition_code(t),
|
|
NT u1, NT u2,
|
|
NT& u) const {
|
|
|
|
#ifndef CGAL_NDEBUG
|
|
NT tmp,s_,t_;
|
|
tmp = CGAL::extended_euclidean_algorithm(m1,m2,s_,t_);
|
|
CGAL_precondition(tmp == NT(1));
|
|
CGAL_precondition(s_ == s);
|
|
CGAL_precondition(t_ == t);
|
|
#endif
|
|
|
|
typedef Algebraic_structure_traits<NT> AST;
|
|
typename AST::Mod mod;
|
|
//typename AST::Unit_part unit_part;
|
|
typename AST::Integral_division idiv;
|
|
|
|
if(u1 < NT(0) ) u1 += m1;
|
|
if(u2 < NT(0) ) u2 += m2;
|
|
|
|
CGAL_precondition(0 < m1);
|
|
CGAL_precondition(u1 < m1);
|
|
CGAL_precondition(u1 >= NT(0));
|
|
|
|
CGAL_precondition(0 < m2);
|
|
CGAL_precondition(u2 < m2);
|
|
CGAL_precondition(u2 >= NT(0));
|
|
|
|
NT v = mod(s*(u2-u1),m2);
|
|
u = m1*v + u1;
|
|
|
|
// u is not unique yet!
|
|
NT m_half = idiv(m-mod(m,NT(2)),NT(2));
|
|
if (u > m_half) u -= m ;
|
|
if (u <= -m_half) u += m ;
|
|
}
|
|
|
|
void operator() (
|
|
const Scalar_type& m1, const Type& u1,
|
|
const Scalar_type& m2, const Type& u2,
|
|
Scalar_type& m, Type& u) const {
|
|
Scalar_type s,t;
|
|
|
|
CGAL::extended_euclidean_algorithm(m1,m2,s,t);
|
|
m = m1 * m2;
|
|
this->operator()(m1,m2,m,s,t,u1,u2,u);
|
|
}
|
|
};
|
|
};
|
|
|
|
} // namespace internal
|
|
} // namespace CGAL
|
|
|
|
#endif // CGAL_CHINESE_REMAINDER_TRAITS_H //
|