/usr/include/CGAL/RS/signat_1.h is in libcgal-dev 4.7-4.
This file is owned by root:root, with mode 0o644.
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//
// 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; either version 3 of the License,
// or (at your option) any later version.
// 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.
//
// $URL$
// $Id$
//
// Author: Luis Peñaranda <luis.penaranda@gmx.com>
#ifndef CGAL_RS_SIGNAT_1_H
#define CGAL_RS_SIGNAT_1_H
#include <CGAL/Gmpfi.h>
#include <CGAL/Polynomial_traits_d.h>
#include "exact_signat_1.h"
//#include <boost/mpl/assert.hpp>
#include <gmp.h>
namespace CGAL{
namespace RS_AK1{
template <class Polynomial_,class Bound_>
struct Signat_1{
typedef Polynomial_ Polynomial;
typedef Bound_ Bound;
typedef CGAL::Polynomial_traits_d<Polynomial> PT;
typedef typename PT::Degree Degree;
Polynomial pol;
Signat_1(const Polynomial &p):pol(p){};
CGAL::Sign operator()(const Bound&)const;
}; // struct Signat_1
template <class Polynomial_,class Bound_>
inline CGAL::Sign
Signat_1<Polynomial_,Bound_>::operator()(const Bound_ &x)const{
typedef Bound_ Bound;
typedef Real_embeddable_traits<Bound> REtraits;
typedef typename REtraits::Sgn BSign;
//typedef Algebraic_structure_traits<Bound> AStraits;
// This generic signat works only when Bound_ is an exact type. For
// non-exact types, an implementation must be provided.
//BOOST_MPL_ASSERT((boost::is_same<AStraits::Is_exact,Tag_true>));
int d=Degree()(pol);
Bound h(pol[d]);
for(int i=1;i<=d;++i)
h=h*x+pol[d-i];
return BSign()(h);
}
template <>
inline CGAL::Sign
Signat_1<Polynomial<Gmpz>,Gmpfr>::operator()(const Gmpfr &x)const{
// In 32-bit systems, using Gmpfr arithmetic to perform exact
// evaluations can overflow. For that reason, we only use Gmpfr
// arithmetic in 64-bit systems.
#if (GMP_LIMB_BITS==64)
typedef ExactSignat_1<Polynomial,Gmpfr> Exact_sign;
#else
typedef Signat_1<Polynomial,Gmpq> Exact_sign;
#endif
// This seems to work faster for small polynomials:
// return Exact_sign(pol)(x);
int d=Degree()(pol);
if(d==0)
return pol[0].sign();
Gmpfi h(pol[d],x.get_precision()+2*d);
Uncertain<CGAL::Sign> indet=Uncertain<CGAL::Sign>::indeterminate();
if(h.sign().is_same(indet))
return Exact_sign(pol)(x);
for(int i=1;i<=d;++i){
h*=x;
h+=pol[d-i];
if(h.sign().is_same(indet))
return Exact_sign(pol)(x);
}
CGAL_assertion(!h.sign().is_same(indet));
return h.sign();
}
// This is the same code as above.
template <>
inline CGAL::Sign
Signat_1<Polynomial<Gmpq>,Gmpfr>::operator()(const Gmpfr &x)const{
typedef Signat_1<Polynomial,Gmpq> Exact_sign;
int d=Degree()(pol);
if(d==0)
return pol[0].sign();
Gmpfi h(pol[d],x.get_precision()+2*d);
Uncertain<CGAL::Sign> indet=Uncertain<CGAL::Sign>::indeterminate();
if(h.sign().is_same(indet))
return Exact_sign(pol)(x);
for(int i=1;i<=d;++i){
h*=x;
h+=pol[d-i];
if(h.sign().is_same(indet))
return Exact_sign(pol)(x);
}
CGAL_assertion(!h.sign().is_same(indet));
return h.sign();
}
} // namespace RS_AK1
} // namespace CGAL
#endif // CGAL_RS_SIGNAT_1_H
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