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// Copyright (c) 2006-2008 Max-Planck-Institute Saarbruecken (Germany).
// 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: svn+ssh://scm.gforge.inria.fr/svn/cgal/branches/next/Modular_arithmetic/include/CGAL/primes.h $
// $Id: primes.h 67093 2012-01-13 11:22:39Z lrineau $
//
//
// Author(s) : Michael Hemmer <hemmer@mpi-inf.mpg.de>
//
// =============================================================================
#ifndef CGAL_PRIMES_H
#define CGAL_PRIMES_H
#include <CGAL/basic.h>
namespace CGAL {
namespace internal {
CGAL_EXPORT extern int primes[2000];
static inline
int get_next_lower_prime(int current_prime){
bool is_prime = false;
int i;
CGAL_precondition_msg(current_prime != 2 ," primes definitely exhausted ");
if((current_prime <= 7) && (current_prime > 2)){
if(current_prime <= 5){
if(current_prime == 3)
return 2;
return 3;
}
return 5;
}
for(i=current_prime-2;(i>1 && !is_prime);i=i-2){
int r = 1;
for(int j=3; (j <= i/2 && (r != 0)); j++){
r = i % j;
// std::cout<<"i " <<i<<std::endl;
// std::cout<<"j " <<j<<std::endl;
// std::cout<<"i%j " <<i%j<<std::endl;
if(j==i/2 && r != 0)
is_prime = true;
}
}
// CGAL_precondition_msg(is_prime," primes definitely exhausted ");
return i+2;
}
}
}
#endif // CGAL_PRIMES_H
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