118 lines
4.2 KiB
C
118 lines
4.2 KiB
C
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// Copyright (c) 2006-2013 INRIA Nancy-Grand Est (France). 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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// See the file LICENSE.LGPL distributed with CGAL.
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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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// Author: Luis Peñaranda <luis.penaranda@gmx.com>
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#ifndef CGAL_RS_SIGNAT_1_H
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#define CGAL_RS_SIGNAT_1_H
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#include <CGAL/Gmpfi.h>
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#include <CGAL/Polynomial_traits_d.h>
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#include "exact_signat_1.h"
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//#include <boost/mpl/assert.hpp>
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#include <gmp.h>
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namespace CGAL{
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namespace RS_AK1{
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template <class Polynomial_,class Bound_>
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struct Signat_1{
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typedef Polynomial_ Polynomial;
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typedef Bound_ Bound;
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typedef CGAL::Polynomial_traits_d<Polynomial> PT;
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typedef typename PT::Degree Degree;
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Polynomial pol;
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Signat_1(const Polynomial &p):pol(p){};
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CGAL::Sign operator()(const Bound&)const;
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}; // struct Signat_1
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template <class Polynomial_,class Bound_>
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inline CGAL::Sign
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Signat_1<Polynomial_,Bound_>::operator()(const Bound_ &x)const{
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typedef Bound_ Bound;
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typedef Real_embeddable_traits<Bound> REtraits;
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typedef typename REtraits::Sgn BSign;
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//typedef Algebraic_structure_traits<Bound> AStraits;
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// This generic signat works only when Bound_ is an exact type. For
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// non-exact types, an implementation must be provided.
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//BOOST_MPL_ASSERT((boost::is_same<AStraits::Is_exact,Tag_true>));
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int d=Degree()(pol);
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Bound h(pol[d]);
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for(int i=1;i<=d;++i)
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h=h*x+pol[d-i];
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return BSign()(h);
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}
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template <>
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inline CGAL::Sign
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Signat_1<Polynomial<Gmpz>,Gmpfr>::operator()(const Gmpfr &x)const{
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// In 32-bit systems, using Gmpfr arithmetic to perform exact
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// evaluations can overflow. For that reason, we only use Gmpfr
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// arithmetic in 64-bit systems.
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#if (GMP_LIMB_BITS==64)
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typedef ExactSignat_1<Polynomial,Gmpfr> Exact_sign;
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#else
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typedef Signat_1<Polynomial,Gmpq> Exact_sign;
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#endif
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// This seems to work faster for small polynomials:
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// return Exact_sign(pol)(x);
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int d=Degree()(pol);
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if(d==0)
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return pol[0].sign();
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Gmpfi h(pol[d],x.get_precision()+2*d);
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Uncertain<CGAL::Sign> indet=Uncertain<CGAL::Sign>::indeterminate();
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if(h.sign().is_same(indet))
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return Exact_sign(pol)(x);
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for(int i=1;i<=d;++i){
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h*=x;
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h+=pol[d-i];
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if(h.sign().is_same(indet))
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return Exact_sign(pol)(x);
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}
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CGAL_assertion(!h.sign().is_same(indet));
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return h.sign();
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}
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// This is the same code as above.
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template <>
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inline CGAL::Sign
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Signat_1<Polynomial<Gmpq>,Gmpfr>::operator()(const Gmpfr &x)const{
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typedef Signat_1<Polynomial,Gmpq> Exact_sign;
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int d=Degree()(pol);
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if(d==0)
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return pol[0].sign();
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Gmpfi h(pol[d],x.get_precision()+2*d);
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Uncertain<CGAL::Sign> indet=Uncertain<CGAL::Sign>::indeterminate();
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if(h.sign().is_same(indet))
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return Exact_sign(pol)(x);
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for(int i=1;i<=d;++i){
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h*=x;
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h+=pol[d-i];
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if(h.sign().is_same(indet))
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return Exact_sign(pol)(x);
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}
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CGAL_assertion(!h.sign().is_same(indet));
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return h.sign();
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}
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} // namespace RS_AK1
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} // namespace CGAL
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#endif // CGAL_RS_SIGNAT_1_H
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