97 lines
2.6 KiB
C
97 lines
2.6 KiB
C
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// Copyright (c) 2002-2008 Max-Planck-Institute Saarbruecken (Germany)
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//
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// This file is part of CGAL (www.cgal.org)
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//
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// $URL: https://github.com/CGAL/cgal/blob/v5.1/Polynomial/include/CGAL/Polynomial/modular_gcd_utils.h $
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// $Id: modular_gcd_utils.h 0779373 2020-03-26T13:31:46+01:00 Sébastien Loriot
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// SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-Commercial
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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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// Dominik Huelse <dominik.huelse@gmx.de>
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//
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// ============================================================================
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/*! \file CGAL/Polynomial/modular_gcd_utils.h
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* \brief Provides additional utils for the modular GCD calculation
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*/
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#ifndef CGAL_POLYNOMIAL_MODULAR_GCD_UTILS_H
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#define CGAL_POLYNOMIAL_MODULAR_GCD_UTILS_H
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#include <CGAL/basic.h>
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#include <vector>
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#include <CGAL/Polynomial.h>
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#include <CGAL/Timer.h>
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namespace CGAL{
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namespace internal {
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template <class NT>
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void euclidean_division_obstinate(const NT& F1, const NT& F2,
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NT& Q, NT& R){
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CGAL_precondition(F2 != 0);
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CGAL::div_mod(F1, F2, Q, R);
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CGAL_postcondition(F1 == F2*Q + R);
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}
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template <class NT>
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void euclidean_division_obstinate(const Polynomial<NT>& F1,
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const Polynomial<NT>& F2,
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Polynomial<NT>& Q, Polynomial<NT>& R){
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// std::cout<<" my_modular_gcd_utils "<<std::endl;
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CGAL_precondition(!F2.is_zero());
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int d1 = F1.degree();
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int d2 = F2.degree();
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if ( d1 < d2 ) {
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Q = Polynomial<NT>(NT(0)); R = F1;
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CGAL_postcondition( !(boost::is_same< typename Algebraic_structure_traits<NT>::Is_exact,
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CGAL::Tag_true >::value) || F1 == Q*F2 + R); return;
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}
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typedef std::vector<NT> Vector;
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Vector V_R, V_Q;
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V_Q.reserve(d1);
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if(d2==0){
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for(int i=d1;i>=0;--i){
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V_Q.push_back(F1[i]/F2[0]);
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}
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V_R.push_back(NT(0));
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}
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else{
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V_R.reserve(d1);
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V_R=Vector(F1.begin(),F1.end());
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Vector tmp1;
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tmp1.reserve(d2);
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for(int k=0; k<=d1-d2; ++k){
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V_Q.push_back(V_R[d1-k]/F2[d2]);
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for(int j=0;j<d2;++j){
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tmp1.push_back(F2[j]*V_Q[k]);
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}
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V_R[d1-k]=0;
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for(int i=d1-d2-k;i<=d1-k-1;++i){
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V_R[i]=V_R[i]-tmp1[i-(d1-d2-k)];
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}
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tmp1.clear();
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}
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}
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Q = Polynomial<NT>(V_Q.rbegin(),V_Q.rend());
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R = Polynomial<NT>(V_R.begin(),V_R.end());
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CGAL_postcondition(F1 == F2*Q + R);
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}
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} // namespace internal
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} // namespace CGAL
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#endif //#ifnedef CGAL_POLYNOMIAL_MODULAR_GCD_UTILS_H 1
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// EOF
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