cgal/Algebraic_kernel_d/include/CGAL/RS/refine_1_rs.h

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// Copyright (c) 2009 Inria Lorraine (France). All rights reserved.
//
// 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.
//
// 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_REFINE_1_RS_H
#define CGAL_RS_REFINE_1_RS_H
#include <gmp.h>
#include <mpfr.h>
#include <mpfi.h>
#include <CGAL/RS/algebraic_1.h>
#include <CGAL/assertions.h>
namespace RS3{
inline void refine_1(const CGAL::Algebraic_1 &a,unsigned int s=10000){
CGAL_precondition(a.inf()<=a.sup());
// If the algebraic endpoints have room for a refinement bigger
// than desired, refine as much is possible. This would ensure that
// small refinements are never made. Other possibility to avoid
// small refinements is to refine the number just after it was
// isolated (this early refinement would also have the advantage
// that one can choose to refine until reaching a certain criterion
// and assume it is true for later refinements, but this can slow
// down the Solve_1 functor). And a last option would be to
// determine a lower bound on the precisions RS likes to refine.
if(s<mpfr_get_prec(&((mpfi_ptr)(a.mpfi()))->left)-2)
s=mpfr_get_prec(&((mpfi_ptr)(a.mpfi()))->left)-2;
if(s<mpfr_get_prec(&((mpfi_ptr)(a.mpfi()))->right)-2)
s=mpfr_get_prec(&((mpfi_ptr)(a.mpfi()))->right)-2;
// If the precision of the endpoints is not enough for the desired
// refinement, allocate a new mpfi and swap later the result.
if(mpfr_get_prec(&((mpfi_ptr)(a.mpfi()))->left)<s+2||
mpfr_get_prec(&((mpfi_ptr)(a.mpfi()))->right)<s+2){
mpfi_t n;
mpfi_init2(n,s+2);
mpfi_set(n,a.mpfi());
rs3_refine_u_root(n,
a.pol().get_coefs(),
a.pol().get_degree(),
s+1,
0,
0);
mpfi_swap(n,(mpfi_ptr)a.mpfi());
// It is not possible to clear the original mpfi because it
// could be allocated inside RS memory.
// TODO: clear the mpfi except the first time it is refined
}else{
rs3_refine_u_root((mpfi_ptr)a.mpfi(),
a.pol().get_coefs(),
a.pol().get_degree(),
s+1,
0,
0);
}
CGAL_postcondition(a.inf()<=a.sup());
}
} // namespace RS3
#endif // CGAL_RS_REFINE_1_RS_H